Multiple coupling facility structures can be defined to increase the number of multinode persistent sessions supported in the sysplex. Multiple structures can be defined on a single coupling facility or across multiple coupling facilities. However, defining multiple structures on one coupling facility increases coupling facility overhead and is not advised.

To implement multiple multinode persistent session structures, define the structures in the MVS™ policy for each associated coupling facility. VTAM® attempts to connect to a base structure and any alternate structures when they are defined in the CFRM policy. See Setting up the sysplex environment for VTAM and TCP/IP functions for information about defining structures used for multinode persistent sessions.

The structure name defined by the STRMNPS start option is the base structure. All other structures used for multinode persistent support are called alternate structures. The name of any alternate structure must begin with the name of the base structure followed by any number of unique and valid characters up to a total of 16 characters. For example, if you specify STRMNPS=ISTMNPS, an alternate structure name could be ISTMNPS01. Care should be taken when using subplexing to avoid generating an MNPS structure name for use in one subplex that might be mistaken as an alternate MNPS structure for a VTAM in another subplex. For example, if a VTAM is started in subplex 11 (that is, start option XCFGRPID=11 is specified), and STRMNPS=ISTMYMNPS is specified, and another VTAM in the sysplex is started with the default subplex (that is, start option XCFGRPID is not specified) and STRMNPS=ISTMYMNPS is specified, then the structure name generated for the MNPS structure in subplex 11 will be ISTMYMNPS11, which will appear to the second VTAM to be an alternate structure to its MNPS structure, ISTMYMNPS. See z/OS Communications Server: SNA Resource Definition Reference for additional information concerning the STRMNPS start option.

You can use the DISPLAY STATS command to view information about the base structure and its associated alternate structures.

Each structure on a coupling facility must have a unique name. If you are using multiple structures, the number of characters used to specify the name of the base structure (STRMNPS start option) must not be too large (to allow unique names for all the alternate structures).