Upgrading the Java environment
If you run Java™ applications in CICS®, whether OSGi, Axis2, or Liberty, you have some changes to make when you upgrade your version of CICS. This information applies to all currently supported CICS TS releases, regardless of your current release and the target release.
Before you start upgrading the Java environment, first upgrade the CICS regions, as described in Upgrading CICS regions.
If you are upgrading from an end-of-service release, you might need to take additional actions that are relevant to your current, end-of-service release. You can find additional upgrade actions for migrating from end-of-service releases in Upgrading from end-of-service releases.
Upgrade actions
Table 1 lists the actions you must perform when upgrading to a higher CICS release, regardless of your current release and the target release. The sections that describe these actions in detail are tagged with All versions.
| Action | Mandatory or optional? |
|---|---|
| Check your programs for deprecated APIs | Optional, but recommended |
| Review your JVM profiles for new settings | Mandatory |
Check your programs for deprecated APIs
All versions
- For more information about deprecated or removed CICS JCICS APIs, see Changes to JCICS API.
- In addition to CICS JCICS APIs, check your programs for deprecated or removed Java APIs. For more information, see Migrating applications to new Java versions.
To avoid potential problems with deprecated APIs, develop all new Java programs for the latest release of CICS using an application development environment that supports the same version of Java as the environment used by CICS. If the older environment does not use APIs that are removed in the newer version of Java or CICS, you can still run code that was compiled with an older version of Java in the new runtime environment. For details, refer to the Target Platform setting when you use the IBM® CICS SDK for Java.
Review your JVM profiles for new settings
All versions
Settings in JVM profiles change from release-to-release so you must upgrade all your JVM profiles. A good practice is to use the sample JVM profiles that come with the latest release, and reapply any customization that you made to those JVM profiles in previous releases.
For more information about the sample profiles, see JVM profile validation and properties. For a summary of the changes to the JVM profiles, see Changes to JVM profiles.