CICS® Transaction Gateway uses the Java™ shared classes feature to improve performance.
Java shared classes provides a transparent and dynamic way of sharing loaded classes that places no restrictions on Java Virtual Machines (JVMs) that are sharing class data. Java shared classes helps reduce virtual memory usage and can improve startup time. CICS Transaction Gateway creates a class cache called cicstgvrm%g, where vrm is the version, release and modification level of CICS Transaction Gateway, and %g is the group name of the user that is running the Gateway daemon job. The cache is created in the /tmp/javasharedresources directory unless the location is overridden with the cachedir sub-option. The class cache options used by the Gateway daemon are output in message CTG6134I during initialization.
The available sub-options are:
-Xshareclasses:name=cicstgvrm%g,groupAccess,nonpersistent,nonfatal
For more information on the Java shared class cache options see your Java documentation.
To override the options used by CICS Transaction Gateway for the -Xshareclasses, set the CTGSTART_OPTS CICS TG environment variable, for example:
CTGSTART_OPTS=-j-Xshareclasses:name=ctgtest%g,cachedir=/tmp/ctgtest,groupAccess,
nonpersistent,nonfatal
To disable class caching for the Gateway daemon, specify the following option:
CTGSTART_OPTS=-j-Xshareclasses:none
To list all the valid sub-options to -Xshareclasses, type the following in the bin directory of your Java installation:
java -Xshareclasses:help
If Gateway daemons using the same Java major version are started on the same LPAR by different user IDs, you must ensure that all user IDs have access to the relevant class cache entities. For more information see your Java documentation.