How global resource serialization works

Depending on the level of z/OS® and XCF environment the systems are running in, sysplex or non-sysplex, a global resource serialization complex consists of one or more systems:

Connected to each other in a ring configuration through:
- XCF signalling paths, through CTC or coupling facility
- Global resource serialization managed channel-to-channel (CTC) adapter
  - Systems in the same sysplex must use XCF signalling
  - Non-sysplex or monplex systems must use GRS-managed CTCs to communicate
Connected to each other in a star configuration through:
- XCF signalling paths, through CTC or coupling facility
- A GRS coupling facility lock structure

Guideline: IBM® recommends basic or parallel sysplex technology for resource sharing. Global resource serialization uses parallel sysplex technology to achieve significant scalability and performance benefits in its star mode. Even with the basic sysplex technology, global resource serialization provides the capability to dynamically change the resource name list (RNL) and provide superior recoverability to ring disruptions. This document uses the term complex because a global resource serialization complex is not the same as a sysplex.

Before looking at the ring and star complexes in more detail, you need to know how users serialize global resources through macros and more about global resource serialization in general.