Dependent regions

The dependent regions are separate address spaces from the control region, which are dependent on IMS and in which IMS schedules the applications that process transactions. Dependent regions are initiated by a z/OS® START command or by a ⁄START REGION command from the IMS master terminal.

The following are different types of dependent regions:

• Message Processing Program (MPP) Region.

  MPP regions are started either by the master terminal operator or by JCL if the control program is running. The control program schedules application programs within the MPP regions. The application programs then run, accessing the online databases and obtaining their transaction input from the message queues. The application programs cannot access z/OS files or issue z/OS checkpoints. The application program output messages can be directed to LTERMs or to other application programs. An application program can remain scheduled in an MPP region even when there is no work to process for that region. The MPP region remains in a wait-state (wait-for-input mode) until there is more work for the region to process.

• Batch Message Processing (BMP) region.

  z/OS schedules the BMP regions. The application programs in those regions are determined by the JCL used to start each region, not by the control region. These application programs can access databases owned by the control region and z/OS data sets owned by their BMP regions. z/OS data sets include data entry databases (DEDBs) and main storage databases (MSDBs).

  Application programs in BMP regions can access input and output message queues; they can also execute in wait-for-input mode. To access the input message queues, you specify, in the JCL for a BMP region, a transaction code you want to access. Specifying this transaction code also gives you access to the output message queues using terminal program communications blocks (PCBs) in the application program's specification block (PSB). Even without access to input message queues, if you specify an output LTERM or transaction code in the JCL for the region, the application program can issue output messages.

• IMS Fast Path (IFP) region.
  Two types of programs run in IFP regions:

  • Application programs for processing Fast Path messages; these are called message-driven programs.
  • Utilities that process DEDBs; these are BMPs.
• Java™ Message Processing (JMP) region.

  JMP regions process messages with either applications written in Java or applications written in both Java and OO COBOL. JMP regions can load 31-bit or 64-bit Java virtual machine (JVM).

• Java Batch Processing (JBP) region.

  JBP regions process batch operations with either applications written in Java or applications written in both Java and OO COBOL. JBP regions can load 31-bit or 64-bit Java virtual machine (JVM).

Related reading:

• For more information on the types of Fast Path processing and the administration of a DB⁄DC environment that includes Fast Path, see IMS Version 15.5 Database Administration.
• For more information on writing applications that can run in JMP and JBP regions, see IMS Version 15.5 Application Programming.