Zowe: Specifying Java overrides

As part of my configuring Zowe, and using Java shared classes, I’ve needed to change the Java parameters in Zowe. I know there is a plan to provide this support – but this is what I’ve done.

Find the start up script.

If you use the Unix command

find zowe/components -name startup.sh

This will list the scripts for the components.

I edited zowe/components/gateway/bin/start.sh and inserted at the top

 COL="/u/tmp/zowec/" 
 
 TAG="GW" 
 fn="${COL}/java.options.${TAG}" 
 if [ -f "${fn}" ]; then 
  set -x 
   export 
   exec 1>>${COL}start.log1${TAG} 2>>${COL}start.log2${TAG} 
   COLIN="-Xoptionsfile=${fn} -XshowSettings " 
 else 
  COLIN="" 
 fi 

and at the bottom of the file

    -Dloader.path=${GATEWAY_LOADER_PATH} \ 
    ${COLIN} \ 
    -jar ${JAR_FILE} &

This code

• checks for a file java.options.GW in the Zowe instance directory.
• If this file exists
  • Create log files in the directory
  • Create an override variable (COLIN), specifying the file name, and telling Java to print out the settings.
• If it doesn’t exist, set the variable (COLIN) to blank
• When the Java command is issued, substitute the variable COLIN – which is either blank, or the options file and display Java options command.

Create the java options file.

You can use

touch java.options.GW

or edit the the and add content.

The output

It produced output like

VM settings: 
    Min. Heap Size: 32.00M 
    Max. Heap Size: 512.00M 
    Using VM: IBM J9 VM 
                                                          
Property settings: 
    XcompilationThreads3 = 
    Xhealthcenter = 
    Xjit:count = 0 
...
JRE 21 z/OS s390x-64-Bit Compressed References 20241024_16 (JIT enabled, AOT enabled) 
OpenJ9   - f45de8e9eb0 
OMR      - 55ddfd47ab0 
IBM      - 3c87141 
JCL      - df334d2be4a based on jdk-21.0.4+7 
    java.home = /Z31B/usr/lpp/java/J21.0_64 
    java.io.tmpdir = /tmp 
....
    xcom.ibm.java.diagnostics.healthcenter.headless.output.directory = /u/tmp/zowec 
                                                                                             
Locale settings: 
    default locale = English (United States) 
    default display locale = English (United States) 
...
Security settings summary: 
    See "java -X" for verbose security settings options 
    Security provider static configuration: (in order of preference) 
        Provider name: OpenJCEPlus 
        Provider name: IBMZSecurity 
        Provider name: SUN 
        Provider name: SunRsaSign 
...
May 29, 2025 9:30:25 AM sun.security.ssl.SSLLogger log 
WARNING: No AlgorithmParameters for sect163k1 
May 29, 2025 9:30:27 AM sun.security.ssl.SSLLogger log 
WARNING: No AlgorithmParameters for sect163r1 
...
    Security TLS configuration (SunJSSE provider): 
        Enabled Protocols: 
            TLSv1.3 
            TLSv1.2