Managing how your Java dependent regions access Db2 for z/OS

Java™ application programs running in IMS dependent regions can access Db2 for z/OS under syncpoint control of z/OS Resource Recovery Services if a DB2® Attach Facility definition is included when the IMS control region is started.

The initialization processing of the IMS control region prepares for access to Db2 for z/OS. When Java dependent regions are subsequently started, application programs in those regions can make direct calls to both Db2 for z/OS and IMS.

Initialization of the DB2 Attach Facility does not affect the execution of other types of dependent regions. The DB2 Attach Facility definition can be retained in the IMS.PROCLIB member, even if Java dependent regions are not used. If a DB2 Attach Facility definition exists in the IMS.PROCLIB member, and the Db2 for z/OS library is defined in the Java dependent region JCL, all Java dependent regions that start will build an access thread to Db2 for z/OS. If the DB2 Attach Facility definition exists, but the Java dependent regions do not require access to Db2 for z/OS, you can prevent access threads from being built by stopping access to the Db2 for z/OS system. Use the /STO SUBSYS command, which stays in effect until a /STA SUBSYS command is subsequently issued.