Intercommunication methods

There are two ways in which CICS® can communicate with other systems: multiregion operation (MRO) and intersystem communication (ISC).

Multiregion operation

For CICS-to-CICS communication, CICS provides an interregion communication facility that is independent of SNA access methods. This form of communication is called multiregion operation (MRO). MRO can be used between CICS systems that reside:

CICS Transaction Server for z/OS® can use MRO to communicate with:

Note:
The external CICS interface (EXCI) uses a specialized form of MRO link to support:

Intersystem communication

For communication between CICS and non-CICS systems, or between CICS systems that are not in the same operating system or MVS sysplex, you normally require an SNA access method, such as ACF/VTAM, to provide the necessary communication protocols. Communication between systems through SNA is called intersystem communication (ISC).

Note:
This form of communication can also be used between CICS systems in the same operating system or MVS sysplex, but MRO provides a more efficient alternative.

The SNA protocols that CICS uses for intersystem communication are:

Additional information on this topic is given in Intersystem communication.

CICS Transaction Server for z/OS can use ISC to communicate with:

Related concepts
Intercommunication facilities
Using CICS intercommunication
Multiregion operation
Intersystem communication
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