JZOS Is a great way of running a Java program on z/OS. The documentation is not clear on how you debug the configuration shell program.
The documentation for the batch launcher and toolkit says:
Java™ Batch Launcher and Toolkit for z/OS® (JZOS) is a set of tools that helps you to develop z/OS Java applications that run in a traditional batch environment, and that access z/OS system services.
Overview
The JZOS Batch Launcher is a native launcher for running Java applications directly as batch jobs or started tasks. Java applications can be fully integrated as job steps to augment existing batch applications.
The JZOS Toolkit is a set of Java classes that give Java applications direct access to traditional z/OS data and key z/OS system services.
The JZOS Batch Launcher and Toolkit includes, but is not limited to, the following facilities and features:
- Run Java applications on z/OS seamlessly in a MVS™ batch job step or started task.
- Simple but flexible configuration of the Java execution environment.
- Access to data sets via JCL DD statements.
- Java interfaces to many z/OS specific APIs and features including SMF, Catalog Search and Logstreams.
- Invoke z/OS Access Method Services (IDCAMS).
- Read and write traditional MVS data sets from Java.
- Communicate with the MVS system console.
- Pass condition codes between Java and non-Java job steps.
- Access z/OS Workload Manager (WLM) services.
The combination of the launcher, data access, added system services, and environmental enhancements make running Java on z/OS as batch jobs easier, particularly for Java application developers. The way that Java batch is managed is now the same as it is for z/OS batch applications written in COBOL, PL/I, or other compiled languages.
Benefits
To me, JZOS is a great way of running JAVA because:
- You need to know very little about OMVS.
- It is one address space.
- Configuring the job to WLM is simple. Configuring for OMVS is harder.
- It is easy to configure.
- You do not have OMVS address spaces(BPXAS) popping up and disappearing in seconds.
- The output can go to the spool, so it is easy to go to the bottom and watch the updates. If you have the output going to a file, you have to edit the file, quit the editor, edit the file etc.
- The output is all in EBCDIC, so you do not get a mixture of ASCII and EBCDIC in a file.
- It is easy to specify CEEOPTS – I could not find how to do it for OMVS address spaces.
- It feels faster – this could be due to run having to run many scripts or command before starting Java.
Configuring JZOS
Example JCL
//S1 EXEC PGM=JVMLDM86,REGION=0M,PARMDD=PARMDD //PARMDD DD *,SYMBOLS=(JCLONLY) /+D -jar /u/ibmuser/aaa/tomcat.home/bin/bootstrap.jar /* //SYSTSPRT DD SYSOUT=* //SYSPRINT DD SYSOUT=* //STDERR DD SYSOUT=* //STDOUT DD SYSOUT=* //STDENV DD * . /u/ibmuser/jzos.sh /* //MAINARGS DD * -config /u/ibmuser/aaa/tomcat.base/conf/sserver.xml start /* //CEEOPTS DD * RPTSTG(ON) */
PGM=JVMLD86 is in my SYS1.SIEALNKE
Where the parmameters are
- / delimiter after C run time parameters
- +D produce debug information
- -jar use a jar rather than a class
- /u/ibmuser/aaa/tomcat.home/bin/bootstrap.jar is my jar name,
In the STDENV you can have statements like
//STDENV DD *
echo "HI HETE"
export JAVA_HOME=/usr/lpp/java/J8.0
export PATH=/bin:"${JAVA_HOME}"/bin
export LIBPATH="$LIBPATH":
echo LIBPATH
/*
or invoke a shell script which uses . (dot) – to run a shell file in the current environment
//STDENV DD * . /u/ibmuser/jzos.sh /*
or combinations of both.
If you have some errors in your definitions, JZOS may not report them.
To debug the script
I changed the job to give loglevel of +D
//PARMDD DD *,SYMBOLS=(JCLONLY) /+D -jar/u/ibmuser/aaa/tomcat.home/bin/bootstrap.jar /*
or set LOGLVL=’+D’ if using the JCL procedure.
I changed by script to add “set -x”
#!/bin/sh set -x
and changed my job
//STDENV DD * exec /bin/sh 1>/tmp/jzos1 2>/tmp/jzos2 . /u/ibmuser/jzos.sh /*
to add the exec statement. It replaces the current shell with /bin/sh and redirects.
After I ran the job, stdout in /tmp/jzos1 and stderr in /tmp/jzos2 provided the output I needed to resolve the problems.
The job will fail because “exec” provides an exit statement, and I got messages like
JVMJZBL1005I Output from DD:STDENV config shell script:
JVMJZBL1009E Child shell process exited without printing environment; //STDENV should not contain ‘exit’
JVMJZBL2999I JZOS batch launcher elapsed time=0 seconds, cpu time=0.070000 seconds
JVMJZBL1042E JZOS batch launcher failed, return code=101
Once you have the shell script running without error, you can comment out
//STDENV DD * # exec /bin/sh 1>/tmp/jzos1 2>/tmp/jzos2 . /u/ibmuser/jzos.sh /*
and JZOS should startup and run your program
ColinPaice 