This section tells you how to customize JVM profiles and properties
files; manage your JVMs and shared class cache; and explains how to idenitfy
problems with your Java applications and JVMs.
Before you begin, verify that the Java components are correctly installed
using the tasks outlined in
Setting
up Java support.
- Set up a JVM profile and JVM properties file to create a JVM for
your Java application.
JVM profiles allow you to specify options
that produce different JVMs depending on your application requirements. Setting up JVM profiles and JVM properties
files tells you how to choose suitable options for your Java applications,
how to use the supplied sample files, and how to customize these samples or
set up your own files.
- Set up and customize a shared class cache for your CICS region,
so that the JVMs can start up faster.
- Setting up the
shared class cache tells you how to set up a shared class cache, and
how to enable JVMs to use it. Most JVMs can use the shared class cache, but
if you do not want certain JVMs to use it, you can set them to run independently
as standalone JVMs.
- Managing the shared class
cache tells you how to alter the shared class cache in your CICS region
while CICS is running. You can customize the shared class cache to prevent
it from starting automatically, adjust its size, update the classes or JAR
files that it contains, or terminate it.
Your CICS region is now ready to create JVMs and run Java applications
in them.
- Enable your application to use a JVM.
- Set the appropriate Java attributes on the PROGRAM resource
definition for the Java program.
- Add the classes for the application to the class paths for the
JVM, which are set by using the options in the JVM profiles and JVM properties
file for the JVM.
Enabling applications to use a
JVM tells you how to perform both of these steps.
- You can monitor the JVMs in your JVM pool, and make tuning adjustments
to achieve optimum performance. Managing your JVMs tells
you how to monitor your JVMs, how to redirect the output from the JVMs, and
how to tune your JVM pool.
- If you have any problems with your JVMs or Java applications, there
are a number of facilities you can use to identify the cause.
- Problem determination for JVMs gives an overview
of the facilities that you can use to identify any problems with your JVMs,
and Controlling tracing for JVMs tells you how to control tracing
for your JVMs
- If a Java application is causing problems, or if you are developing
new Java applications, you can use debugging tools to examine and debug an
application while it is running in a JVM. Debugging an application that is running in a CICS JVM tells
you how to set up a JVM for debugging, and how you can use debugging tools
and plugins with a JVM.
Note that the older type of JVM that was introduced in CICS® Transaction Server for OS/390®, Version 1 Release 3 is
no longer supported. Any Java programs that ran under CICS Transaction Server for OS/390, Version 1 Release 3,
and were not previously migrated for CICS Transaction Server for z/OS®, Version 2,
must be migrated to Java 2 to run under the persistent reusable JVM. Removal of support for CICS Transaction Server for OS/390, Version 1 Release 3 JVMs has more information about this.