This section outlines the operation of CICS® regions in a multiregion environment using the multiregion operation (MRO) or intersystem communication (ISC) to communicate between CICS regions.
It assumes that you have already defined your multisystem environment, and are familiar with the concepts of CICS intercommunication facilities, as described in the CICS Intercommunication Guide.
You should consider using CICSPlex® System Manager (CICSPlex SM) to manage multiple CICS regions. Those CICS regions can be:
For information about CICSPlex SM, see the CICSPlex SM Concepts and Planning manual, SC33-0786.
To provide the optimum transaction processing environment for your online business applications, you may choose to spread the workload of your business applications across several CICS regions. You can exploit the CICS intercommunication facilities to communicate between the CICS regions, and from CICS to other types of systems (such as IMS™).
The CICS intercommunication facilities that you can use are:
Using ISC, the hosts can be different operating systems, and the communicating systems do not both have to be CICS. For example, a CICS Transaction Server for z/OS®, Version 3 Release 1 region running in an MVS image can communicate with a CICS/VSE partition running under VSE/ESA. Alternatively, on two MVS platforms, the communicating systems could be CICS at one end and IMS at the other.
Using CICS intercommunication facilities, CICS functions can be separated into individual regions, the different types of CICS region being classified as resource managers. These CICS resource managers can reside in one or more MVS images. However, if they are in different MVS sysplexes, communication must be ISC. CICS regions in the same MVS image (or the same sysplex) can use MRO, which is the preferred method for performance reasons.
CICS regions segregated into resource-manager regions are generally known by the name of the principal resource they "own". The names used in this book are summarized in the Preface.
Intersystem communication and Multiregion operation in the CICS Intercommunication Guide contain information about CICS intercommunication, and how to implement both intersystem communication and multiregion operation. This section assumes that you are familiar with the CICS intercommunication facilities.