Setting up TCP/IP and VTAM® subplexes within a sysplex requires some preparation.

To prepare your sysplex for subplexing, perform the following steps:

1. If there are TCP/IP stacks that use the subplexed VTAM nodes, see setting up a sysplex in topic in z/OS Communications Server: IP Configuration Guide.
2. If the TCP/IP stack subplex configuration (determined in the previous step) requires the use of HiperSockets™ VLAN IDs (using the IQDVLANID parameter on the GLOBALCONFIG TCP/IP profile statement), ensure that all VTAM nodes in the sysplex are at z/OS® V1R8 or later.
3. If VTAM coupling facility structures for generic resources or MNPS are to be used, ensure that all the structures have been defined to z/OS and are specified in the active CFRM policy using their fully suffixed names. For example, if the generic resources function is to be used with the base structure name of ISTGENERIC, and two VTAM subplexes are to be configured, one subplex with a suffix of 11 and the other with a suffix of 12, then ensure that the ISTGENERIC11 and ISTGENERIC12 structures are defined to MVS™ and specified in the active CFRM policy.
4. For each VTAM that needs to specify an XCFGRPID value or supports TCP/IP stacks that need to be changed to specify an XCFGRPID value or IQDVLANID value on their GLOBALCONFIG statements, do the following steps:
   1. If this VTAM requires a new XCFGRPID value, stop VTAM
   2. For each TCP/IP stack supported by this VTAM that requires a new XCFGRPID or IQDVLANID value:
      1. Stop the TCP/IP stack.
      2. Update the GLOBALCONFIG statement in the TCP/IP profile for this stack with the new XCFGRPID and IQDVLANID values.
      3. Restart the TCP/IP stack.
   3. If VTAM was stopped, update the VTAM start options to add the new XCFGRPID option with the group ID value for the new subplex (or specify the new XCFGRPID start option when prompted, after starting VTAM).
   4. Restart the VTAM node.