In a star complex, requests for ownership of global resources will be handled through ISGLOCK, the lock structure, on a coupling facility that is fully connected with all the systems in the sysplex. Global resource serialization uses the ISGLOCK lock structure to reflect a composite system level view of the interest in every global resource, for which there is at least one requester. In general, global resource serialization alters this composite view each time you change the set of requesters for the resource.

Each time an ENQ request is received, global resource serialization processing analyzes the state of the resource request queue for the resource. If the new request alters the composite state of the queue, an IXLLOCK macro request is made to reflect the changed state of the resource for the requesting system. If the resource is immediately available, the requester is then granted ownership of the resource.

If the resource is not immediately available, global resource serialization will maintain the request in the waiting state. When the appropriate DEQ request is received, global resource serialization will either resume or post the requester (depending on the ENQ options).