When is activity trace enabled?

I found the documentation for activity trace was not clear as to the activity trace settings.

In mqat.ini you can provide information as to what applications (including channels) you want traced.

For example


This file and trace value are checked when the application connects.  If you have TRACE=ON when the application connects, and you change it to TRACE=OFF, it will continue tracing.

If you have TRACE=OFF specified, and the application connects, changing it to TRACE=ON will not produce any records.


  • TRACE=ON, the application will be traced
  • TRACE=OFF the application will not be traced
  • TRACE= or omitted then the tracing depends on alter qmgr ACTVTRC(ON|OFF).   For a long running transaction using alter qmgr to turn it on, and then off, you will get trace records for the application from in the gap.

If you have



then program progput will have trace turned on because the definition is more specific.

You could have



to  be able to turn trace on for all programs beginning with prog, but not to trace progzzz.


Thanks to Morag of MQGEM  who got in contact with me, and said  long running tasks are notified of a change to the mqat.ini file, if the file has changed, and a queue manager attributed has been changed – even if it is changed to the same variable.

This and lots of other great info about activity trace (a whole presentation’s worth of information) is available here.

Would you lock your front door and leave the key under the mat? So why do you do it with digital keys?

Where I live it is Island Mentality. Someone said to me that they do not lock their front door. Sometimes, when they come home, they find some eggs or tray-bakes on the kitchen table. They went on a celebration cruise, but could not find the key to the front door, and so left the house unlocked the two weeks they were away.

Digital certificates and keys are used for identification authentication. Often these are stored in a key store, just a file in Windows or Unix. You typically need a password to be able to read the file. If you got hold of a keystore, you could try “password” with an “o”, “passw0rd” with zero etc. There is no limit to the number of attempts you can have. Don’t worry, the password is stored in a stash file , which is just another file. If you have the key store and the stash file you can open the keystore using standard commands. Having both the keystore and the stash file is like finding the front door unlocked.

If someone is an administrator on the machine, they can access any file and so can get the keystore and the stash file. IBM says you need superuser access to install MQ – so the MQ administrator can access these files. I heard that one enterprise was doing backups from the user’s machines to a remote site. The files were encrypted at the remote site, but not the network link to the remote site – whoops! The files could have been stolen en route.

Use external security devices.

You can get round this problem by using an external Hardware Security Module. Instead of storing the keys in a file, they are stored on an external device. You can get USB like devices. Some HSM can store keys, other HSMs can encrypt data. For example my bank gives its user’s a small machine. You put in your debit card, enter your pin. It encrypts the data and generates a one time key which you enter into the bank’s web site.

To steal the keystore you now need access to the physical machine to be able to unplug the USB.

Built in devices that cannot be removed.

On some machines, such as z hardware, they have a tamper resistant “cryptographic chip” built in. If you remove it from the machine, it is useless. When you configure it you need three keys, so you have three people each with their own key. When you install the backup machine, the three people have to go on site, and re enter their keys. They have mechanisms like three wrong passwords and it self destructs (perhaps in a cloud of smoke, as it does in the movies).


One of the selling points of cloud is flexibility. You can deploy an image anywhere; you can wheel in new machines, and wheel out old machines; and you can have different “tenants” on the same hardware. This makes it difficult to use an HSM device to store your keys, as each machine needs the same keys, and the HSM could have all the keys from all the tenants. So you have the problem, of having your key store as a file with its stash file, and even more people have access to these files.

Would you lock your front door and leave the key under the mat? So why do you do it with digital keys

It is all down to the management of risk. Digital certificates do not give absolute protection. Strong encryption just means it takes longer to crack!

Certificate logon to MQWEB on z/OS, the hard way.

I described here different ways of logging on to the MQ Web Server on z/OS. This post describes how to use a digital certificate to logon. There is a lot of description, but the RACF statements needed are listed at the bottom.

I had set up my keystore and could logon to MQWEB on z/OS using certificates. I just wanted to not be prompted for a password.

Once it is set up it works well. I thought I would deliberately try to get as many things wrong, so I could document the symptoms and the cure. Despite this, I often had my head in the hands, asking “Why! – it worked yesterday”.

Can I use CHLAUTH ? No – because that is for the CHINIT, and you do not need to have the CHINIT running to run the web server.

Within one MQ Web Server, you can use both “certificate only” logon as well as using “certificate, userid and password” logon.

When using the SAF interface you specify parameters in the mqwebuser.xml file, such as keyrings, and what level of certificate checking you want.

Enable SAF messages.

If you use <safCredentials suppressAuthFailureMessage=”false” …> in the mqwebuser.xml then if a SAF request fails, there will be a message on the z/OS console. You would normally have this value set to “true” because when the browser (or REST client) reauthenticates (it could be every 10 seconds) you will get a message saying a userid does not have access to an APPL, or EJBROLE profile. If you change this (or make any change the mqwebuser.xnml file), issue the command

f CSQ9WEB,refresh,config

To pick up the changes.

Configure the server name

In the mqwebuser.xml file is <safCredentials profilePrefix=”MQWEB“…> there MQWEB identifies the server, and is used in the security profiles (see below).

SSL parameters

In the mqwebuser.xml file you specify

  • <ssl …
  • clientAuthenticationSupported=”true”|”false. The doc says The server requests that a client sends a certificate. The client’s certificate is optional
  • clientAuthentication=”true”|”false” if true, then client must send a certificate.
  • ssslProtocol=”TLSV1.2″
  • keyStoreRef=”…”
  • trustStoreRef=”…”
  • id=”…”
  • <sslDefault … sslRef=”…” this points to a particular <ssl id=…> definition. It allows you to have more than one <ssl definition, and pick one.

I think it would have been clearer if the parameters were clientAuthentication=”yes”|”no”|”optional”. See my interpretation of what these mean here.

Client authentication

The client certificate maps to a userid on z/OS, and this userid is used for access control.

The TLS handshake: You have a certificate on your client machine. There is a handshake with the server, where the certificate from the server is sent to the client, and the client verifies it. With TLS client authentication the client sends a certificate to the server. The server validates it.

If any of the following are false, it drops through to Connecting with a client certificate, and authenticate with userid and password below.

Find the z/OS userid for the certificate

The certificate is looked up in a RACDCERT MAP to get a userid for the certificate (see below for example statements). It could be a one to one mapping, or depending on say OU=TEST or C=GB, it can check on part of the DN. If this fails you get

ICH408I USER(START1 ) GROUP(SYS1 ) NAME(####################)

Check the userid against the APPL class.

The userid is checked against the MQWEB profiles in the APPL class. (Where MQWEB is the name you configured in the web server configuration files). If this fails you get


Pick the EJBROLE for the userid

There are several profiles in the EJBROLES class. If the userid has read access to the class, it userid gets the attribute. For example for the profile MQWEB.com.ibm.mq.console.MQWebAdmin, if the userid has at least READ access to the profile, it gets MQWEBADMIN privileges.
If these fail you get messages in the MQWEB message logs(s).

To suppress the RACF messages use option suppressAuthFailureMessage=”false” described above.

The userid needs access to at least one profile to be able to use the MQ Web server.

Use the right URL

The URL is like

No password is needed to logon. If you get this far, displaying the userid information (click on the ⓘ icon) gives you Principal:ADCDE – Read-Only Administrator (Client Certificate Authentication) where ADCDE is the userid from the RACDDEF MAP mapping.

Connecting with a client certificate, and authenticate with userid and password.

The handshake as described above is done as above. If clientAuthentication=”true” is specified, and the handshake fails, then the client gets This site can’t be reached or similar message.

If the site can be reached, and a URL like is used, this displays a userid and password panel.

The password is verified, and if successful the specified userid is looked up in the APPL and EJBROLES profiles as described above.

If you get this far, and have logged on, displaying the userid information (click on the ⓘ icon) gives you Principal:colin – Read-Only Administrator (Client Certificate Authentication) where colin is the userid I entered.

The short solution to implement certificate authentication

If you already have TLS certificates for connecting to the MQ Web Server, you may be able to use a URL like to do the logon. If you use an invalid URL, it will substitute it with .

My set up.

I set up a certificate on Linux with a DN of C=GB,O=cpwebuser,CN=ADCDC and signed by C=GB,O=SSS,OU=CA,CN=SSCARSA1024. The Linux CA had been added to the trust store on z/OS.

Associate a certificate with a z/OS userid

I set up a RACF MAP of certificate to userid. It is sensible to run these using JCL, and to save the JCL for each definition.

    SDNFILTER('CN=ADCDC.O=cpwebuser.C=GB') - 
    WITHLABEL('CA       ') 

This mapped the certificate CN=ADCDC.OU=cpwebuser.C=GB to userid ADCDE. Note the “.” between the parts, and the order has changed from least significant to most significant. For other certificates coming in with the Issuer CA of CN=SSCARSA1024.OU=CA.O=SSS.C=GB they will get a userid of ADCDZ.

You do not need to refresh anything as this change becomes visible when the SETROPTS RACLIST REFESH is issued.

First logon attempt

I stopped and restarted my Chrome browser, and used the URL I was prompted for a list of valid certificates. I chose “Subject:ADCD: Issuer:SSCARSA1024 Serial:0194”.

Sometimes it gave me a blank screen, other times it gave me the logon screen with username and Password fields. It had a URL of

On the z/OS console I got


I could see the the userid(ADCDE) from the RACDCERT MAP was being used (as expected). To give the userid access to the MQWEB resource, I issued the commands


And tried again. The web screen remained blank (even with the correct URL). There were no messages on the MQWEB job log. Within the MQWEB stdout (and /u/mqweb/servers/mqweb/logs/messages.log) were messages like

[AUDIT ] CWWKS9104A: Authorization failed for user ADCDE while invoking com.ibm.mq.console on
/ui/userregistry/userinfo. The user is not granted access to any of the required roles: [MQWebAdmin, MQWebAdminRO, MQWebUser].

Give the userid access to the EJBroles

In my mqwebuser.xml I have <safCredentials profilePrefix=”MQWEB”. The MQWEB is the prefix of the EJBROLE resource name. I had set up a group MQPA Web Readonly Admin (MQPAWRA) to make the administration easier. Give the group permission, and connect the userid to the group.

 /* RDEFINE EJBROLE MQWEB.com.ibm.mq.console.MQWebAdminRO  UACC(NONE) 
PERMIT MQWEB.com.ibm.mq.console.MQWebAdminRO CLASS(EJBROLE) - 

Once the security change has been made, it is visible immediately to the MQWEB server. I clicked the browser’s refresh button and successfully got the IBM MQ welcome page (without having to enter a userid or password). When I clicked on the ⓘ icon it said

Principal:ADCDE – Read-Only Administrator (Client Certificate Authentication)

Logoff doesn’t

If you click the logoff icon, you get logged off – but immediately get logged on again – that’s what certificate authorisation does for you. You need to go to a different web site. If you come back to the ibmmq/console web site, it will use the same certificate as you used before.

Ways of logging on to MQWEB on z/OS.

There are different ways of connecting to the MQ Web Server on z/OS (this is based on the z/OS Liberty Web server). Some ways use the SAF interface. This is an interface to the z/OS security manager. IBM provides RACF, there are other security managers such as TOP SECRET, and ACF2. Userid information is stored in the security manager database.

The ways of connecting to the MQ Web server on z/OS.

  • No security. Use no_security.xml to set up the MQ Web Server.
  • Hard coded userids and passwords in a file. Using the basic_registry.xml. This defines userid information like <user name=”mqadmin” password=”mqadmin”> . This is suitable only for a sandbox. The password can be obscured or left in plain text.
  • Logon by z/OS userid and password. Use zos_saf_registry.xml. Logon is by userid and password and checked by a SAF call to the z/OS security manager. The userid is checked for access to a resource like MQWEB.com.ibm.mq.console.MQWebAdmin in class(EJBROLE) and MQWEB in class(APPL).
  • Connect with a client certificate, and authenticate using userid and password. This uses zos_saf_registry.xml plus additional configuration. The userid, password and access to the EJBROLE and APPL resources is checked by the SAF interface. The certificate id is not used to check access, it is just used to do the TLS handshake.
  • Certificate authentication, a password is not required. Connecting use a client certificate. This uses zos_saf_registry.xml plus additional configuration. Using the SAF interface, the certificate maps to a z/OS userid; this ID is used for checking access to the EJBROLE and APPL resource.

The configuration for using TLS is not clear.

I found the documentation for the TLS configuration to be unclear. Two parameters are <ssl clientAuthentication clientAuthenticationSupported…/> The documentation says

  • If you specify clientAuthentication="true", the server requests that a client sends a certificate. However, if the client does not have a certificate, or the certificate is not trusted by the server, the handshake does not succeed.
  • If you specify clientAuthenticationSupported="true", the server requests that a client sends a certificate. However, if the client does not have a certificate, or the certificate is not trusted by the server, the handshake might still succeed.
  • If you do not specify either clientAuthentication or clientAuthenticationSupported, or you specify clientAuthentication="false" or clientAuthenticationSupported="false", the server does not request that a client send a certificate during the handshake.

I experimented with the different options and the results are below.

  1. I used a web browser with several possible certificates that could be used for authentication. I was given a pop up which listed them. Chrome remembers the choice. With Firefox, you can click an option “set as default“. If this is unticked you get prompted every time.
  2. I used a browser with no certificates for authentication.

When a session was not allowed, I got (from Firefox) Secure Connection Failed. An error occurred during a connection to PR_END_OF_FILE_ERROR

Client AuthenticationClient Authentication SupportedBrowser with certificatesBrowser without certificates
trueignoredPick certificate, userid and password NOT requiredPR_END_OF_FILE_ERROR
falsetruePick certificate, userid and password NOT requiredA variety of results. One of
  2. Blank screen
  3. Userid and password required
falsefalseUserid and password requiredUserid and password required

When using certificates, you can chose to specify userid and password instead of client authentication, by using the appropriate URL with, instead of .

Note well.

The server caches credential information. If you change the configuration and refresh the server, the change may not be picked up immediately.

Once you have logged on successfully, a cookie is stored in your browser. This may be used to authenticate, until the token has expired. To be sure of clearing this token I restarted my browser.

Are you going crazy with Chrome giving fatal: certificate_unknown, bad_certificate NET::ERR_CERT_INVALID? Me too!

I came back to using Chrome with my MQ Web browser. It was working last week, but yesterday and today it stopped working. In debugging it, I’ve learned even more ways of checking TLS handshakes to see why they fail!

Using Wireshark packet trace on Linux, and TLS trace in the web server, I could see the Client Hello, Server hello, worked; but the response was Chrome giving NET::ERR_CERT_INVALID, and the traces showing Alert Level: Fatal, Description: Certificate Unknown.

  • I had been through the checks to make sure the CA was in the client key store.
  • I double checked, and tripled checked to make sure it was the right CA.
  • I exported the z/OS CA certificate, downloaded it and imported it.
  • I displayed the z/OS version, and the Chrome keystore’s version and they matched ( ok – the not-after and not-before times were different due to different time zones).
  • I shut every thing down and restarted it the next day.
  • I felt like screaming “AHH -it worked last week it works on FireFox – it should all work on Chrome”

After a day workingb in the garden, I had time to consider a different approach.

How I traced the problem down.

From your browser you can display the “problem” certificate by clicking on the icon in front of the URL. You get into “certificate viewer”. There is a “General” display which shows you useful information about the certificate. There is also the “Details”. At the bottom of the Details is a button labelled “Export”. Click it and export the certificate to a file such as SERVER.PEM.

You can now use openssl on this. For example

openssl x509 -in ~/Downloads/SERVER.cert.bad -text -noout|less

This shows you all the details of the certificate, so you can check them again!

You can also export the CA you think is being used, from the browser keystore, eg CA.pem

You can use the openssl verify command to do its validation of the server certificate and the CA certificate.

openssl verify -CAfile ca.pem -show_chain ~/Downloads/SERVER.cert

worked, it gave

depth=0: O = ZZZZ, OU = SSS, CN = SERVER (untrusted)
depth=1: O = TEMP, OU = TEST, CN = TEMP4Certification Authority

Which shows the server certificate, and the CA certificate were OK. However the same command with -x509_strict gave

openssl verify -CAfile ca.pem -show_chain -x509_strict ~/Downloads/SERVER.cert


error 24 at 0 depth lookup: invalid CA certificate
error /home/colinpaice/Downloads/SERVER.cert.bad: verification failed

I felt I was on the trail of the problem.

Depth 0 is the server certificate. Depth 1 is the signers certificate, Depth 2 is the next level up. It was strange that it said the server certificate was an invalid CA.

Looking in the openssl source openssl/crypto/x509/x509_vfy.c showed several lines giving the error code X509_V_ERR_INVALID_CALL.

It turns out that the server’s certificate had been configured to to “certsign” (I had mis-copied a line in the certificates definition from an earlier test). Certsign means the certificate is a CA because it can sign things – but the CA flag was not set in the certificate – so clearly it was a bad_certificate. The validation failed – as it failed the consistency check it reported unknown certificate, and I was getting very frustrated.

What keyusage is required?

Any keyusage from no keysusage to KEYUSAGE( DATAENCRYPT, DOCSIGN, HANDSHAKE) works.

Just do not use KEYUSAGE(CERTSIGN) .

Recreate the certificate, and add it to the key store, and use

f CSQ9WEB,refresh,keystore

to get the MQ web server to pick up the change to the keystore. You may need to restart your web browser.

I think this is a useful technique which I will use in the future when I stumble over the next TLS set up problem.

How to do an SSL/TLS trace in Firefox

I was trying to configure a firefox session to my MQ Web server, but it kept failing. I found a useful way of getting the TLS trace from firefox.

My web site was

The command ssltap -s sets up a proxy. It listens on a port (default 1924). In firefox use https://localhost:1924/ibmmq/console/ 1>aa 2>bb. This then talks to the proxy which then talks to the backend. Not perfect but OK.

Hints and tips for using WordPress.

I’ve been using WordPress for a couple of years now.  On the whole it has been pretty easy, but sometime I struggled, until I found a work around.  I’ll document some of these.

How do I find my document?

I have many blog posts and found it hard to find the one I wanted.  You can display all your posts using Posts -> All Posts.

  • Use the Dates pull down, select a month, and press filter.  This shows me the documents I’ve created on in the selected month.
  • Use the Categories pull down, select one, and press filter.  This shows the matching documents.  You specify the categories when you make the post.
  • Tab across, enter a search argument and press the Search Posts button.

How do I find my drafts ?

On the dashboard page -> Quick draft has recent drafts and view all drafts.

Creating a post

You can use the “classic” or the “block” mode.  I prefer classic for small posts as I find it easier to use and uses less key strokes.

With a classic block you can enter headings, data, tables etc.  With block mode, you create a heading block, or a text block or a pre formatted block, or a native html block. A block may be one sentence.

How to edit the html in classic mode

If you go to the top of the document it will display two toolbars, use the “⋮” in the smaller toolbar.  Select “Edit as html”.   Go down to your text… make your changes, and select the “⋮” in the small box toolbar which appears as you move the cursor.  With big documents this gets impractical, so using block mode may be better.

You can be in block mode, but create small blocks of classic mode. I do this when I want to change attributes, for example in the style sheet example below, I could only add style=”line-height :90%; ” to the <pre… >, if I used classic mode. If you do not use classic mode, it removes the “failing” code. It gets a bit messy, but you get used to it.

Pasting text into pre formatted blocks.

You can create a pre formatted block.  This is basically data within a <pre>…</pre> set of html tags.

If you paste into a block, it removes multiple spaces, and so all your nicely formatted text comes out all wrong.  The solution is to go into html mode, find the <pre>…</pre> and paste your text.   This will retain multiple spaces.

I find the data displayed in a pre formatted block is too large.  I use

<pre><small>….  my data </small></pre> to make the text smaller, see below for an example.

Using tables

You can use the blocks mode “table” to define a table, then edit it as raw html to do tweaks, such as change the width of columns as in the following example.

    <th width=”30%“>header1</th>

Using Style Sheets

Here is a link to information on CSS and style sheets.  You can search for attributes such as line-height.

I have not found a way of including a style sheet in a page.  If you edit the html you can use  inline styles for example

<span style=”color:red;”>…</span>,

or use CSS for example selectors like

  • <pre class=”tls”>…</pre> with CSS class definition .tls {}
  • <pre id=”special>…</pre> with CSS id definition #special{}
  • <pre>…</pre> with CSS tag definition  pre {}
  • or combinations <pre class=”tls”>…/pre> with CSS pre.tls {} meaning <pre> tags and class = tls.

then specify the style via WordPress home page -> Appearance-> Customize -> Additional CSS.  This means what you put in this section is available to all your posts and pages. 

I have

pre.tls, div.tls {
line-height: 1;
color: darkgreen;

This says any pre html tags with class=”tls”, or a div tag with a class=”tls” set the line height to 1, and make the color darkgreen.

My style sheet includes

/* reduce the vertical space of lists */
.compact {
line-height: 90%;
/* make the summary line look link a link, by underlining it and changing
the colour. Also change the cursor to a hand
details > summary {
background-color: #ddd;
border: none;
text-decoration: underline;
cursor: pointer;
/* Make <b> bolder within <pre class="tls" */
pre.tls b {
font-weight: 900;
color: black;

 Note: the above pre formatted text has style=”line-height : 90%” in the <pre > tag, and the <small>…</small> tags have been used.

What are my top posts?

Dashboard -> Top pages and posts.   This gives Today, Yesterday; tab across to Summaries,  Select from  7 Days| 30 Days| Quarter| Year| All Time

How to rearrange the dashboard.

You can drag and drop with widgets

The widgets within dashboard have “˄, ˅” at the top.   This moves the widget up or down. (Up means up the right hand side to the bottom of the left, then up the left hand side to the top)

  • ⏶ close widget
  • ⏷ open widget

What are the short cuts?

I found this document which has a good list.

Adding pictures

You can add pictures via your media. Use the Add Media icon in the toolbar (Alt shift M), select from your list, and click on “Insert” .  The are strict controls as to the types of data you can upload.

Why do they ship java products on z/OS with the handbrake on? And how to take the brake off.

I noticed that it takes seconds to start MQ on my little z/OS machine, but minutes (feels like days) to start anything with Liberty Web server.  This include the MQWEB, z/OSMF,  and Z/OSConnect.  I mentioned this to an IBM colleague who asked if I was using Java Shared classes.  These get loaded into z/OS shared pages.

When I implemented it, my Liberty server came up in half the time!

I found this blog post which was very helpful, and showed me where to look for more information.  I subsequently found this document (from 2006!)

The kinder garden overview of how Java works.

  • You start with a program written in the Java language.
  • When you run this, Java converts it into byte codes
  • These byte codes get converted to native instructions  – so a byte code “push onto the stack” may become 8  390 assembler instructions.
  • This code can be optimised, for example code which is executed frequently can have the assembler instructions rewritten to go faster.  It might put code inline instead of out in a subroutine.
  • If you are using Java shared classes, this code can be written out and reused by other applications, or if you restart the server, it can reused what it created before.  Reusing the shared classes means that programs benefit because the byte codes have already been converted into native code, and optimisations have been done on the hot code.

What happens on z/OS?

By default, z/OS writes the code to virtual memory and does not save anything to disk.  If you restart your Java application within the same IPL, it can exploit the shared classes which have been converted to native code, and optimised – great- good design.   I found the second time I started the web server it took half the time.  However I IPL once a day, and start my web server once a day. I do not benefit from having it start faster a second time – as I only started it once per session. By default when you re-ipl, the shared classes code is discarded, and so next time you need the code, it has to be to convert to native instructions again, and it loses any optimisation which had been done.

What is the solution?

It is two easy steps:!

  1. Tell Java to write the information from memory to disk – to take a snaphot.
  2. After IPL tell Java to load memory from the disk image – to restore a snapshot.

It is as simple as that.


It is all to do with the java -Xshareclasses.

With your application you tell Java where to store information about the shared classed.  It defaults to Cache=/tmp/ name=javasharedresources.

In my jvm.options I overrode the defaults and specified


If you give each application a name (such as mqweb)  you can isolate the cache to an application and not disrupt another JVM if you change the cache.  For example if you restore from a snapshot, only users of that “name” will be affected.

List what is in the cache

You can use the USS command,

java -Xshareclasses:cacheDir=/tmp/,listAllCaches

I used a batch job to do the same thing.

// SET V='listAllCaches' 
// SET C='/tmp/' 
// PARM='SH java -Xshareclasses:cacheDir=&C,&V' 
//STDOUT   DD   SYSOUT=*            

The output below, shows the cache name is mqweb.  Once you have created a snapshot it has an entry for it.

Listing all caches in cacheDir /tmp/                                                                          
Cache name       level         cache-type      feature         OS shmid       OS semid 
mqweb            Java8 64-bit  non-persistent  cr              8197           4101 

For MQWEB the default parameters are -Xshareclasses:cacheDir=/u/mqweb/servers/.classCache,name=liberty-%u” where /u/mqweb is the WLP parameter, where my parameter are defined, and %u is the userid the server is running under, so in my case liberty=START1.

When I had /u/mqweb/servers/.classCache, then the total command line was too long for BPXBATCH.   (Putting it into STDPARM gave me IEC020I 001-4 on the instream STDPARM because the resolved line wa greater than 80 characters.   I resolved this by adding -Xshareclasses:cacheDir=/u/mqweb,name=cache to the jvm.options file.

To take a snapshot

// SET C='/tmp/' 
// SET N='mqweb' 
// SET V='restoreFromSnapshot' 
// SET V='listAllCaches'
// SET V='snapshotCache' //S1 EXEC PGM=BPXBATCH,REGION=0M, // PARM='SH java -Xshareclasses:cacheDir=&C,name=&N,&V' //STDERR DD SYSOUT=* //STDOUT DD SYSOUT=* //

This job took a few seconds to run.

I believe you have to take the snapshot while your java application is executing – but I do not know for definite.

Restore a snapshot

To restore a snapshot just use restoreFromSnapshot in the above JCL. This took a few seconds to run. 

How to use it.

If you put the restoreFromSnaphot JCL at the start of the web server, it will preload it whenever you use your server.

If you take a snapshot every day before shutting down your server, you will get a copy with the latest optimisations.  If you do not take a new snapshot it continues to use the old one.

If you want to not use the shared cache you can get rid of it using the command destroySnapshot.

Is my cache big enough?

If you use the printStats request you get information like

Current statistics for cache "mqweb":                                                
cache size                           = 104857040                                     
softmx bytes                         = 104857040                                     
free bytes                           = 70294788 
Cache is 32% full                                     
Cache is accessible to current user = true                                                 

The documentation says

When you specify -Xshareclasses without any parameters and without specifying either the -Xscmx or -XX:SharedCacheHardLimit options, a shared classes cache is created with a default size, as follows:

  • For 64-bit platforms, the default size is 300 MB, with a “soft” maximum limit for the initial size of the cache (-Xscmx) of 64MB, …

I had specified -Xscmx100m  which matches the value reported.

What is in the cache?

You can use the printAllStats command.  This displays information like


1: 0x00000200259F279C CLASSPATH

Methods for a class
  • 0x00000200259F24A4 ROMCLASS: java/util/HashMap at 0x000002001FF7AEB8.
  • ROMMETHOD: size Signature: ()I Address: 0x000002001FF7BA88
  • ROMMETHOD: put Signature: (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object; Address: 0x000002001FF7BC50

This shows

  • there is a class HashMap. 
  • It has a method size() with no parameters returning an Int.  It is at…. in memory
  • There is another method put(Object o1, Object o2)  returning an Object.  It is at … in memory
Other stuff

There are sections with JITHINTS and other performance related data.


Getting SSL/TLS to work on MQ on z/OS

After I succeeded in getting TLS 1.3 to run on MQ  midrange 9.2, I thought I would try it on z/OS.  I had not used TLS on z/OS for about 10 years, so it was almost like coming to the topic with very rusty knowledge.

I searched the Knowledge centre and found no relevant hits – lots of hits which were not relevant.  I eventually found an SSL related keyword, and this got me to the topic  Working with SSL/TLS on z/OS.   I think this is well documented.  It covered all the things I had to do.

The remained of this post covers the bits not covered by the documentation.


You need to define SSLTASKS to be able to use TLS on z/OS.  See the comments here. I used


You need to restart the CHINIT if you change the value of SSLTASKS.

Set up the keyring for the queue manager. 

See here.  This post show how to create the keyring and import a CA from z/OS, and import a CA  from a Linux system.

If you alter the keyring or certlabl you just need a refresh security type(SSL) command to pick up the changes.

Defining the channel

I tried to define the channel, as this failed for security reasons, I’ve given the RACF setup I had to do.

In this section I defined the specific commands for example DEFINE.CHANNEL.   I could have defined DEFINE.* to allow all define commands.

I used a channel called TLS, and define the resource CSQ9.CHANNEL.TLS* to allow my ID to define TLS, TLS1 etc

The command %CSQ9 DEF CHL(TLS) CHLTYPE(SVRCONN) gave me


I used the RACF commands in a batch job.


I also set up CSQ9.DELETE.CHANNEL and CSQ9.ALTER.CHANNEL in a similar way, so my userid could maintain the channels.

I refreshed MQ security %CSQ9 refresh security to pick up the changes.

I reissued the command %CSQ9 DEF CHL(TLS ) CHLTYPE(SVRCONN) and got


I used the RACF commands in a batch job.


I issued the commands

%CSQ9 refresh security

And successfully defined the channel.

I changed the cipher spec.

I selected a cipher spec from the list.

%CSQ9 alter chl(TLS) chltype(SVRCONN) SSLCIPH(ECDHE_RSA_AES_128_CBC_SHA256)

When I started the channel I got

CSQX631E … CSQXRESP Cipher specifications differ,  channel TLS local=ECDHE_RSA_AES_128_CBC_SHA256 remote=TLS_RSA_WITH_AES_256_GCM_SHA384
connection (

This was clear;  I love clear messages.

I decided to change the z/OS end

%CSQ9 alter chl(TLS) chltype(SVRCONN) SSLCIPH(TLS_RSA_WITH_AES_256_GCM_SHA384 )

and the client connected successfully.

With MQ 9.2 I could (and did) change this to

%CSQ9 alter chl(TLS) chltype(SVRCONN) SSLCIPH(ANY_TLS12)

and the client worked successfully.  The ANY_TLS12.  provides a wide list of supported cipher specifications, includes TLS_RSA_WITH_AES_256_GCM_SHA384  and ECDHE_RSA_AES_128_CBC_SHA256. 

When I am ready to support TLS 1.3 I will use ANY_TLS12_OR_HIGHER and ANY_TLS13_OR_HIGHER.

Connect a client to it!

I had had my client connect to a midrange queue manager, so I had working client environment.  See here for the journey.

I created a .json file for the CCDT connection to z/OS.  I specified

{ "channel":
    "name": "TLS",
        "host": "",
        "port": 1414
      "queueManager": "CSQ9"
      "cipherSpecification": "ANY_TLS12",
      "certificateLabel": "rsaca256_client",
      "certificatePeerName": ""
    "type": "clientConnection"

When it connected I got messages

+CSQX511I %CSQ9 CSQXRESP Channel TLS started connection
+CSQX512I %CSQ9 CSQXRESP Channel TLS no longer active connection

COLINPAI came from the userid on the Linux machine (colinpaice) upper cased and truncated. This id will be flowed and used as the MCAUSER if you don’t set it to anything else, using CHLAUTH for example  (Thanks to Morag for this information).

Enable chlauth

To be able to map from the DN in a certificate to a z/OS userid you have to use MQ CHLAUTH.  See  Mapping a client user ID to an MCAUSER user ID.

Check it is enabled at the queue manager level and enable it it needed.


Define a mapping from certificate to userid

I used

//SYSIN   DD * 
     TYPE(SSLPEERMAP) SSLPEER('O="cpwebuser"') + 

This says for channel TLS,  take the Organisation(O=..)  from the certificate, and if it is cpwebuser then set the ID to ADCDD.

Check it works

Once the channel had started I used

it displayed the following, where I have removed lines which are not relevant to TLS and added some comments

  • SECPROT(TLSV12) – this is the level of the protocol
  • SSLCERTI(CN=SSCARSA1024,OU=CA,O=SSS,C=GB)- this is the DN of the issuer of the SSLPEER certificate (below)
  • SSLCERTU(START1) – the IBM documentation says “The local user ID associated with the remote certificate.”  I dont know where this comes from.. how to change it, or where it is used.
  • SSLCIPH(TLS_RSA_WITH_AES_256_GCM_SHA384) – The negotiated cipher spec
  • SSLRKEYS(0) -The number of successful TLS key resets.
  • SSLKEYTI() -The time on which the previous successful TLS secret key was reset.  The secret key has not been reset
  • SSLKEYDA() -The date on which the previous successful TLS secret key was reset.  The secret key has not been reset
  • SSLPEER(SERIALNUMBER=01:90,CN=rsaca256,O=cpwebuser,C=GB, UNSTRUCTUREDNAME=openssl_ca_user_cnf.keyAgreement2, UNSTRUCTUREDNAME=localhost, UNSTRUCTUREDADDRESS= . This is information from the certificate at the remote end.
  • MCAUSER(ADCDD) – This is the userid (set by the CHLAUTH above) used by this channel.
  • LOCLADDR( – This is the address the connection came in from.  This value will be different it you have different IP stacks and different listener ports.

Taking the brakes off ZFS on z/OS – move it to OMVS

From z/OS 2.2 there is a performance advantage in running the ZFS file system as part of OMVS, rather than its own address space.  The IBM documentation says When running zFS in the OMVS address space, each file system vnode operation (such as creating a directory entry, removing a directory entry, or reading from a file) will have better overall performance. Each operation will take the same amount of time while inside zFS itself. The performance benefit occurs because z/OS UNIX can call zFS for each operation in a more efficient manner.  This will be relevant when you application is doing a lot of file IO – for example using a web server.

This move is not documented – but it is really easy!  It is mentioned here. Instructions are hidden in the installation instructions here.

Before I started

The IBM doc says You can determine if zFS is in its own address space by issuing D OMVS,PFS. If the output shows an ASNAME value, zFS is running as a colony address space.

OMVS     0010 ACTIVE             OMVS=(00,01,BP,IZ,RZ,BB)                
PFS CONFIGURATION INFORMATION                                            
  ZFS       IOEFSCM    ZFS       LOCAL     A     2021/02/17 17.35.06 

The steps I took…

  2. Being ultra cautious I re-ipled.
  3. The documentation talks about putting IOEZPRM DD in OMVS, then goes on to say As the preferred alternative to the IOEZPRM DDNAME specification, delete the IOEZPRM DDNAME and use the IOEPRMxx parmlib member.  So I did not change the OMVS proc.  When I reipled it worked and I got the message IOEZ00374I No IOEZPRM DD specified in OMVS proc. Parmlib search being used. 
  4. I edited USER.Z24A.PARMLIB(BPXPRM00) and removed the ASNAME in  FILESYSTYPE TYPE(ZFS) ENTRYPOINT(IOEFSCM)ASNAME(ZFS) Well I actually made a copy of the original line and put it between /* and */, then deleted the text.
  5. I reipled.


The  D OMVS,PFS command now gives  N/A instead of the Address Space Name

OMVS     0010 ACTIVE             OMVS=(00,01,BP,IZ,RZ,BB)                
PFS CONFIGURATION INFORMATION                                         
  ZFS       IOEFSCM    N/A       LOCAL     A     2021/02/17 17.55.47  


The hardest part was making sure I had an IPLable SARES1 in case I got it wrong!

Issuing commands…

I used to issue commands like f zfs,query,all. Now that the ZFS address space does not exist, you need to use  f omvs,pfs=zfs,query,all.

Setting up the MQ keyring on z/OS

I wanted to connect some clients to my z/OS queue manager over a TLS channel.  This post describes how I set up the z/OS keyring with the certificates.

Define the keyring.

The CSQ9 CHINIT runs with a userid of START1, so I defined a keyring belonging to that id.

I set up a dataset  called IBM.MQCSQ9.KEYRING to keep all of my JCL in for the CSQ9 queue manager.  This makes it easier to clone the definitions for another queue manager.

The definitions create the keyring, and add the z/OS CA certificate (CERTAUTH ADCD_CA) to it.

//* Use JCL for the RACF definitions

Define the queue manager’s certificate.   This uses an Elliptic curve with key size of 256.

             O('ADCD') - 
             OU('TEST')) - 
   SIZE(256) - 

It need ALTNAME(IP( ( or similar) because some browsers check this name, with the IP address of the server.


Configure the queue manager


Note if you use mixed case keyring you need to put the value in quotes.

Export the CA certificate from z/OS and sent to the client machine


The data set  IBMUSER.CERT.ADCDCA.PEM  contained text, and the first line is —–BEGIN CERTIFICATE—– .   Send this file to the client machine, for example using FTP.  I sent it as zos.adcdca.pem.

Import this to the keystore

runmqakm -cert -add -file zos.adcdca.pem -type cms -stashed -db zzclient.kdb -label zosca

Upload  the certificates from Linux to z/OS.

On Linux, my CA certificiate was in a *.pem file where the first line was —–BEGIN CERTIFICATE—–.  Send this to z/OS.  I used FTP.

Import the CA into the keyring.

The command adds an existing certificate CARSA1024 for userid START1.  The CONNECT USAGE(CERTAUT) defines this as a CA certificate (without the need to have the certificate belong to CERTAUTH userid).

                             USAGE(CERTAUTH) - 
                             ID(START1)  - 
 racdcert listring(MQRING ) id(start1) 

Refresh the queue manager

%CSQ9 refresh security type(SSL)