Sysplex couple data sets and joining a sysplex

A system can IPL into the sysplex if either of the following is true:

Its COUPLExx parmlib member specifies, on PCOUPLE and ACOUPLE keywords, sysplex couple data sets that match those of the active sysplex.
Its COUPLExx parmlib member specifies a sysplex couple data set that matches one previously used by at least one of the active systems in the sysplex.

MVS™ issues messages to a system that IPLs with COUPLExx specifications for couple data sets that do not match those currently in effect in the sysplex. To eliminate these messages, edit the COUPLExx member to reflect the current primary and alternate couple data sets in the sysplex. If sysplex primary or alternate data sets need to be deleted, first delete their specifications from each system's COUPLExx parmlib member.