Installing the JZOS batch launcher

If you install IBM® Semeru Runtime Certified Edition for z/OS® by using SMP/E, JZOS is installed for you. If you install the product from a PAX file, you must follow these instructions to be able to use the JZOS batch launcher.

Before you begin

These instructions assume that you uploaded and extracted the PAX file according to the Java™ SDK product installation instructions. For more information, see Installing the SDK.

Note: If you do not follow these instructions, you cannot use the JZOS batch launcher function. However, you can use all other JVM functions, including the JZOS system services and file I/O functions.

About this task

The launcher consists of the following files:

JVMLDM21, a load module that you add to a z/OS PDSE data set.
JVMPRC21, a customizable sample PROC file that you add to an appropriate procedure library (PROCLIB).
JVMJCL21, a customizable sample JCL file that you add to an appropriate sample library (SAMPLIB).

Procedure

Allocate MVS PDSE or PDS data sets as required. As an example, a default SMP/E installation places the load module in the SYS1.SIEALNKE data set, the sample PROC file in the SYS1.PROCLIB library and the sample JCL file in the SYS1.SAMPLIB library. (For installation into private data sets, suggested allocation sizes are F/FB,80 5 tracks for SAMPJCL and for SAMPPROC.)
Copy the load module to a PDSE data set. Copy the PROC and JCL files to a PDS data set. The load module is in the <JAVA_HOME>/mvstools directory. The sample JCL and PROC files are in the <JAVA_HOME>/mvstools/jcl directory.
For example, by using the default target libraries, issue the following commands under a z/OS UNIX System Services shell:
```
cp jcl/JVMJCL21 "//’SYS1.SAMPLIB(JVMJCL21)’"
cp jcl/JVMPRC21 "//’SYS1.PROCLIB(JVMPRC21)’"
cp -X JVMLDM21 "//’SYS1.SIEALNKE(JVMLDM21)’"
```
Compile the HelloWorld.java program included in the JZOS samples. Then, place the compiler-generated HelloWorld.class class file in an accessible location in your z/OS UNIX System Services file system.
Customize the sample JCL and PROC files for your environment.
- Update the JCL file with JOB card information.
- Update the JCL and PROC files with high-level qualifiers where the PROC and LOADLIB exist.
- Update the CLASSPATH variable in the JCL file to include the directory, in your z/OS UNIX System Services file system, containing the compiled HelloWorld.class file from step 3.
- Update the value of the JAVA_HOME environment variable in the PROC file.
- Ensure that your sample JCL or PROC file includes a STEPLIB statement to point to the load module, unless the load module is included in your LNKLST member.
Run the modified JCL script by using the SUBMIT command, then check the job log. For a correct set up, the SYSOUT DD output should contain information like this:
```
21.0.1-internal" 2023-10-17
IBM Semeru Runtime Certified Edition for z/OS (build 21.0.1-internal-adhoc.JORAN.openj9-openjdk-jdk21-zos)
IBM J9 VM (build ibm_sdk-83007b4a526, JRE 21 z/OS s390x-64-Bit Compressed References 20231231_000000 (JIT enabled, AOT enabled)
OpenJ9   - 83007b4a526
OMR      - b9e66a5b6
IBM      - 7394519
JCL      - 3448fcd02b1 based on jdk-21.0.1+12)
```
To diagnose problems with the JZOS batch launcher, change the LOGLVL parameter to +I:
```
// EXEC JVMLDM21,LOGLVL=’+I’,
```
Note: Setting this logging level dumps the environment that is passed to the Java VM. The trace level setting +T produces many messages, some of which can be helpful in tracking down installation problems.