Chapter 7. Problem determination 185
򐂰 Application-related subsystem connectors
򐂰 XML toolkit or parser in use on z/OS
򐂰 Java for z/OS
The most up-to-date information about operating system prerequisites for correct
JVM operation is found at IBM’s Java for z/OS Web site:
http://www.ibm.com/servers/eserver/zseries/software/java/
In addition, any new prerequisites are described in PTF HOLDDATA.
Keeping and tracing this information can be very helpful to determine if the
problem is caused by wrong maintenance levels or mismatched maintenance
levels. Sometimes the maintenance level changes can make your application
malfunction.
If you talk to the IBM support team, they will ask you to provide this basic
information so that they can assist you in investigating the problems.
7.2.2 LE settings
The JVM running on z/OS is written in C/C++. The z/OS Language Environment
(LE) Runtime Options (RTOs) affect operation of C and C++ programs.
In general, you should not use your own LE RTOs to override the options that
were set by the JVM developers using C #pragma statements in the code. These
options are generated as a result of extensive testing to provide the best possible
operation of the JVM.
If you do need to override some of the LE RTOs for some reason, we
recommend you do some testing to evaluate the impact on the JVM and
document the changes for future problem determination.
7.2.3 Environment variables
Environment variables that change the operation of the IBM JVM in one release
can be deprecated or change meaning in a following release. Therefore, you
should review environment variables that are set for a specific release of the
JVM to verify that they still apply after a future upgrade.
Any JVM or other software upgrade can make your environment variables such
as PATH, LIBPATH, CLASSPATH, and so forth no longer valid. You need to
double check the USS environment variables in your USS shell scripts and JCLs
to ensure they are still valid.

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