Starting dependent regions

IMS dependent regions are z/OS® regions that are separate from the IMS control region, and that are logically dependent upon the IMS control region.

The following types of programs execute in dependent regions:

IMS batch message programs (BMPs) and message processing programs (MPPs)
IMS Fast Path (IFP) message-driven application programs
Fast Path DEDB online utility programs
Java™ batch processing (JBP) and Java message processing (JMP) applications
Coordinator controller (CCTL) application programs (in the IMS DBCTL environment)

You can start IMS dependent regions from the z/OS system console or the IMS master terminal. From the z/OS system console, use the z/OS START command to start a reader procedure (usually IMSRDR) to read the JCL for the region. From the IMS master terminal, use the IMS /START REGION command to start a region. If you do not specify a procedure name on the START or /START REGION command, IMS uses the IMSMSG procedure.

You should not start IMS message regions and Fast Path regions with automatic priority group (APG) initiators because IMS cannot control the dispatching priority of an APG-initiated job or uniquely identify such jobs. You might need to start and stop z/OS initiators for IMS message regions and Fast Path regions that have APG initiators.

IMS can dynamically allocate up to 255 regions. The total number of regions includes the number of regions allocated during IMS system definition plus the number of dynamically allocated regions or CCTL threads.