The coordinating address space (CAS) is an MVS subsystem whose main function is to support the MVS/TSO ISPF end-user interface (EUI) to CICSPlex® SM. The CAS is not part of a CICSplex, but belongs to the managing topology of CICSPlex SM. (See Figure 2).
A CAS need not be started on every MVS system where a CMAS runs
to provide Single System Image (SSI) function for EUI requests directed at
a CICSplex. However in order for an EUI user to set the context to a CMAS, that
CMAS must be connected to an active CAS.