Setting up the shared class cache

The shared class cache explains how the shared class cache works, and how JVMs benefit from using it.

CICS® supports one active shared class cache in each region. This enables you to support the majority of the JVMs in each region. Some of the JVMs in the region might not be suited to sharing the class cache, because they have an inappropriate level of reusability, or because they are debug JVMs used for problem diagnosis. These JVMs can still run as standalone JVMs, and have their own cache of classes in their storage heaps.

Before setting up the shared class cache, you need to check the options for semaphores that you have set in the BPXPRMxx members of SYS1.PARMLIB. The master JVM that initializes the shared class cache uses a single semaphore ID, and requests a set of 32 semaphores, so you need to: See z/OS UNIX System Services Planning, GA22-7800, in the topic “Customizing the BPXPRMxx parmlib members”, and z/OS MVS Initialization and Tuning Reference, SA22-7592, in the topic “BPXPRMxx (z/OS UNIX System Services parameters)“, for more information about adjusting these parameters. The CICS Transaction Server for z/OS® Installation Guide has information about other parameters in the BPXPRMxx members of SYS1.PARMLIB that need to be changed to use JVMs in a CICS environment.

Now that you have set up a shared class cache in your CICS region, Managing the shared class cache tells you how to manage it.