Constraints and usage notes

Only a single J9VM in an address space is supported.

Only one observation at a time is supported for a particular J9VM in an address space.

IMS™ Java™ programs are supported in Java Message Processing (JMP) and Java Batch Processing (JBP) regions by using the preloaded Application Performance Analyzer JVMTI agent. To preload the Application Performance Analyzer JVMTI agent, add the -agentpath runtime parameter to the JVM options member that is specified in the JVMOPMAS parameter on the DFSJMP and DFSJBP procedures. Typically this is the DFSJVMMS member in the IMS PROCLIB data set.

CICS® Java programs are supported for CICS/TS 4.2 and above.

The Application Performance Analyzer JVMTI agent will stop sampling when the main thread ends, even if the specified number of samples has not been reached.

J9VM sampling can only be carried out if there is more than one CPU allocated to the system image on which it runs.

Depending on the processor speed of the system, Application Performance Analyzer might reduce the sampling rate of a J9VM observation.

The Application Performance Analyzer JVMTI agent uses about 2.5MB of heap storage. It might be more or less at your installation.

When J9VM sampling support is enabled for a dynamically loaded JVMTI agent, a J9VM is launched in the Application Performance Analyzer started task address space. This increases the amount of storage used by the started task. The real storage pages may increase to about 10 times the usual amount.

The J9VM launched in the started task is configured to use a 4MB heap. It is also configured not to use any zAAP processors.

For more information about using the Java Attach API, please see the User Guide for IBM® SDK for z/OS® for the Java release you are running.