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.

A CICS region can be part of a CICSplex or a single CICS region that is not part of any CICSplex.

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.