For a function (such as, CFRM, ARM, or SFM) to be used by the sysplex, the couple data set containing the policy and/or data associated with that function must be accessible to all systems that need to use it. If a system cannot access a function couple data set, then the system does not use that function. Any policy associated with that function does not become active on that system.

When formatting a function couple data set, IBM strongly recommends that you use a MAXSYSTEM value equal to the value used to format the primary sysplex couple data set. Using a smaller value can prevent a system from using the function couple data set, as described in Implications of the MAXSYSTEM value for the sysplex couple data set. Using a larger value results in an unnecessarily large couple dataset, wastes system storage, and degrades I/O performance. Beginning with z/OS V1R12, the (IBMXCF,XCF_CDS_MAXSYSTEM) health check reports on any function couple data set formatted with a MAXSYSTEM value less than that used for the sysplex couple data set.

The CFRM couple data set must have connectivity to all systems in the sysplex that use the coupling facility. If a system using a CFRM data set loses connectivity to the data set, the system is placed in a non-restartable wait state.