CICS® multiregion operation (MRO) enables CICS systems 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™.
ACF/VTAM 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:
CICS regions linked by MRO can be at different release levels; see Multiregion operation. If an MVS image contains different releases of CICS, all using MRO to communicate with each other (or XCF/MRO to communicate with regions in other images in the sysplex), the DFHIRP module in the MVS LPA should be that from the most current CICS release in the image, or higher. For full details of software and hardware requirements for XCF/MRO, see Requirements for XCF/MRO.
Installation of CICS multiregion operation is described in Installation considerations for multiregion operation.