Selecting a Coupling Facility for Structure Allocation

The system allocates a structure in a coupling facility based on the requirements that the installation has specified in its active CFRM and sysplex failure management policies, and in accordance with the attributes specified on the IXLCONN macro. Prior to allocating the structure, the system may or may not reorder the preference list to reflect the coupling facility that most closely meets the allocation criteria.

The CFRM policy not only lists structure names and sizes, but also defines preference lists and exclusion lists. A preference list is an ordered list of the coupling facilities in your installation in which you would prefer having a structure allocated. An exclusion list is an unordered list of coupling facility structures which you do not want to reside in the same coupling facility as this specific structure.
The SFM policy assigns a weight to each system in the sysplex designating the system's relative importance in the sysplex.

How the system selects a coupling facility for structure allocation depends on whether the installation has specified that the preference list order is to be enforced. The CFRM policy statement, ENFORCEORDER(YES), available with on systems with OW33615 installed or which are running OS/390® Release 9 or higher, specifies that the system is to enforce the order of the coupling facilities in the preference list for structure allocation, and is not to reorder the list based on how well the coupling facilities meet the structure's allocation requirements. See Preference List Order Enforced.