When you upgrade to a new CICS® release, you might require changes to your JVM profiles and to other aspects of your Java™ environment. You might also require changes to your Java applications.
Earlier versions of Java
Java programs that ran under CICS Transaction Server for z/OS®, Version 3 and CICS Transaction Server for z/OS, Version 4 can also run under CICS Transaction Server for z/OS, Version 5.
When
you upgrade from one version of Java to
another, check for compatibility issues between the Java APIs, and compatibility issues specific
to the IBM® SDK for z/OS. You can find this information at 
Java Standard
Edition Products on z/OS.
To avoid potential problems with deprecated APIs, develop all new Java programs for CICS Transaction Server for z/OS, Version 5 Release 2 using an application development environment that supports the same version of Java as the environment used by CICS. You can run code compiled with an older version of Java in a new runtime environment, if the environment does not use APIs that are removed in the newer version of Java or CICS. For further details refer to the Target Platform setting when using the CICS Explorer® SDK.
JVM profiles
If you already have JVM profiles that you set up in a previous CICS release, upgrade these profiles. Settings that are suitable for use in JVM profiles can change from one CICS release to another, so check the CICS documentation for any significant changes. You must also compare your existing JVM profiles to the latest samples supplied with CICS. Changes to the JVM profile options are described in Changes to options in JVM profiles. A list of suitable options for this release is in JVM profiles: options and samples. Use the new samples supplied with CICS Transaction Server for z/OS, Version 5 Release 2 to help you create new profiles, rather than upgrading your existing files.
Copy your JVM profiles to a new location on z/OS UNIX to use with the new CICS release then apply the required upgrades. Do not try to use JVM profiles with more than one CICS release at the same time, because the settings are not compatible.
Ensure that the JVM profiles that you want to use are in the z/OS UNIX directory that is specified by the JVMPROFILEDIR system initialization parameter.
