Component TRACE (CTRACE) is the z/OS system trace capability for z/OS components. Most z/OS components use it.

From “capturing a trace” perspective, there are two aspects.

• Capturing the trace data
  • The trace can be an in-memory trace, which is available when a dump is taken. This is is often the default. For example by default a trace is enabled to capture errors, and the in-memory trace is used.
  • You can have a trace writer started task which writes to a data set. When you start the trace you give the name of the started task. Data is passed to the trace writer job. You can then use the trace data set in IPCS.
• Enabling the trace for the component. Usually there are options you can specify, for example all entries, or just error entries and how big the in-memory trace should be.

To trace a z/OS component, you need to know the CTRACE component name, and what you want to trace.

I tried to capture a CTRACE of a z/OS component, and struggled, because I didn’t know the name of the component.

What are the trace component names?

The z/OS command

TRACE STATUS         

gave

IEE843I 16.10.22  TRACE DISPLAY 940                               
        SYSTEM STATUS INFORMATION                                 
 ST=(ON,0001M,00005M) AS=ON  BR=OFF EX=ON  MO=OFF MT=(ON,064K)    
 COMPONENT MODE  COMPONENT MODE  COMPONENT MODE  COMPONENT MODE   
 --------------------------------------------------------------   
 CSF       ON    NFSC      ON    SYSGRS    MIN   SYSANT00  MIN    
 SYSJES2   SUB   SYSRRS    MIN   SYSIEAVX  MIN   SYSSPI    OFF    
 SYSJES    SUB   SYSHZS    MIN   SYSSMS    OFF   SYSAXR    MIN    
 SYSDLF    MIN   SYSOPS    MIN   SYSXCF    MIN   SYSDUMP   ON     
 SYSLLA    MIN   SYSXES    ON    SYSUNI    OFF   SYSCATLG  MIN    
 SYSTTRC   OFF   SYSTCPDA  SUB   SYSRSM    SUB   SYSAOM    MIN    
 SYSVLF    MIN   SYSTCPIP  SUB   SYSLOGR   ON    SYSOMVS   MIN    
 SYSCEA    MIN   SYSWLM    MIN   SYSTCPIS  SUB   SYSTCPRE  SUB    
 SYSIOS    MIN   SYSANTMN  MIN   SYSDMO    MIN   SYSIEFAL  ON     
 SYSTCPOT  SUB                                                    

I was after a CEA trace, and from the above, the name is SYSCEA. It is MIN, so is already active.

What is the trace’s status?

d trace,comp=SYSCEA

gave me

COMPONENT     MODE BUFFER HEAD SUBS                           
------------------------------------------------------------- 
SYSCEA        MIN  0002M                                      
   ASIDS      *NONE*                                          
   JOBNAMES   *NONE*                                          
   OPTIONS    ERROR                                           
   WRITER     *NONE*                                          

So it is active, capturing errors, and writing to the in-memory trace (because there is no WRITER). I recognised the options as the defaults in parmlib member CTICEA00.

I had my own trace writer started task

Member CTWTR in proclib

//CTWTR PROC                                                                  
//DELETE  EXEC PGM=IEFBR14                                                    
//TRCOUT01 DD DSNAME=IBMUSER.CTRACE1,                                         
// SPACE=(CYL,(10),,CONTIG),DISP=(MOD,DELETE)                                 
//*                                                                           
//IEFPROC EXEC PGM=ITTTRCWR,TIME=999                                          
//TRCOUT01 DD DSNAME=IBMUSER.CTRACE1,                                         
// SPACE=(CYL,(10),,CONTIG),DISP=(NEW,CATLG)                                  
//SYSPRINT DD SYSOUT=*                                                                

I started my CTRACE writer

TRACE CT,WTRSTART=CTWTR          

I created my own member CTICEACP in parmlib

TRACEOPTS 
   ON 
   BUFSIZE(20m) 
   OPTIONS('ALL') 
   WTR(CTWTR) 

The WTR ties up with my CTRACE writer started task name.

Stop the current trace

TRACE CT,OFF,COMP=SYSCEA

Start the CEA trace using my member

TRACE CT,ON,COMP=sysCEA,PARM=CTICEACP

Run the test

Stop the CEA trace

TRACE CT,OFF,COMP=SYSCEA

Stop the trace writer

TRACE CT,WTRSTOP=CTWTR     

The output from the CTWTR task gave me

IEF196I IEF142I CTWTR CTWTR - STEP WAS EXECUTED - COND CODE 0000         
IEF196I IGD104I IBMUSER.CTRACE1                              RETAINED,   
IEF196I DDNAME=TRCOUT01                                                  

which gives me the name of the data set IBMUSER.CTRACE1.

Use IPCS to look at the trace

• option =0 to specify the name of the data set
• =6
• dropd
• The above command clears out any old information about the data set
• CTRACE COMP(SYSCEA) full

I had some data in the trace – but not for the problem I had…. so I need to try something else.

The advanced class.

You do not need to have a member in parmlib. You can use

TRACE CT,ON,COMP=SYSCEA

and do not specify a PARM. This will then prompt for the parameters, asid, jobname, writer and options.