CICS topology

You can distribute CICS applications and the resources they use between interconnected CICS regions. You can group CICS regions into CICS system groups and CICSplexes, and distribute regions across the z/OS systems in a sysplex.

Figure 1. How CICS regions are organized in a sysplex
An illustration of the relationship between z/OS systems, CICSplexes, CICS systems groups, and CICS regions in a sysplex.
The following terms are used when discussing CICS topology:
Sysplex

A set of z/OS systems that communicate and cooperate with each other through multisystem hardware components and software services.

CICS region

An named instance of CICS Transaction Server that runs in its own z/OS address space. A CICS region can be started and stopped independently of other CICS regions.

CICSplex
A grouping of CICS regions that is managed as a single entity. Each CICS region can belong to one CICSplex only. A CICSplex can include CICS regions running on different z/OS systems in a sysplex.
CICS system group
A grouping of CICS regions in a CICSplex that can be managed as a single entity. A system group can include CICS regions running on different z/OS systems. In a CICSplex, each CICS region can belong to more than one system group, and system groups can be contained in other system groups.