JVM 64-bit support migration considerations

Specify JVM=64 in the EXEC job control statement to enable the JVM 64-bit support. The JVM= parameter is valid only for Java™ batch processing (JBP) and Java message processing (JMP) regions.

By default, Java dependent regions load and run with a 31-bit Java virtual machine (JVM). You can modify the JVM addressing mode to 64-bit by specifying the JVM=64 parameter in the DFSJBP and DFSJMP procedure EXEC statement. The new JVM= parameter is valid only for the JBP and JMP regions.

When you specify the JVM= parameter on the EXEC PGM=DFSRRC00 card for the JMP region, you must specify all positional parameters, PRLD=, SSM=, PARDLI=, MINTHRD= and MAXTHRD=, before the JVM= parameter. MAXTHRD= and MINTHRD= are two positional parameters that are hidden when the JVM= parameter is not provided.

By specifying JVM=64, Language Environment®, the infrastructure that supports a 64-bit JVM, is also changed to the 64-bit addressing mode.

You can change to the default 31-bit addressing mode by specifying JVM=31.

To determine which addressing mode a JVM in a Java dependent region is using, you can check the JVM= parameter, the environment file, or the status messages in the job output.

Example

The following sample output shows status messages of a job that uses 31-bit JVM. In the 31-bit addressing mode, the DFSJVM00 module is used, and the LIBPATH points to a 31-bit JVM directory.

DFSJVM00: ENVIRON member name is DFSJVMEV   
DFSJVM00: LIBPATH=/usr/lpp/java170/J7.0/bin/
DFSJVM00: JVMOPMAS member name is DFSJVMMS

In the following sample output of a job that uses 64-bit JVM, the DFSJVM64 module is used, and the LIBPATH points to a 64-bit JVM directory.

DFSJVM64: ENVIRON member name is DFSJVMEV
DFSJVM64: LIBPATH=/usr/lpp/java170/J7.0_64/bin/
DFSJVM64: JVMOPMAS member name is DFSJVMMS