Interregion communication (IRC)
CICS® multiregion operation (MRO) enables CICS regions that are running in the same MVS™ image, or in the same MVS sysplex, to communicate with each other. MRO does not support communication between a CICS system and a non-CICS system such as IMS. 1
ACF/Communications Server and SNA networking facilities are not
required for MRO. The support within CICS that
enables region-to-region communication is called interregion communication (IRC).
IRC can be implemented in three ways:
- Through support in CICS terminal control management modules and by use of a CICS-supplied interregion program, DFHIRP, loaded in the MVS link pack area. DFHIRP is invoked by a type 3 supervisory call (SVC).
- By MVS cross-memory services, which you can select as an alternative to the CICS type 3 SVC mechanism. Here, DFHIRP is used only to open and close the interregion links.
- By the cross-system coupling facility (XCF) of MVS. XCF is required for MRO links between CICS regions in different MVS images of an MVS sysplex. It is selected dynamically by CICS for such links, if available.
This section describes the communication part of MRO. Multiregion operation (MRO) gives a brief description of multiregion operation.
1 The external CICS interface (EXCI) uses a specialized form of MRO link to support communication between MVS batch programs and CICS.