A coupling facility is a special logical partition that runs the coupling facility control code (CFCC) and provides high-speed caching, list processing, and locking functions in a sysplex.
HCD enables you to specify whether a logical partition can be a coupling facility, operating system, or either on certain processors. You connect the coupling facility logical partition to a processor through the coupling facility channels.
With z/OS services, a component called XES allows authorized applications, such as subsystems and z/OS components, to use the coupling facility to cache data, exchange status, and access sysplex lock structures in order to implement high performance data sharing and rapid recovery from failures.
The coupling facility is defined using HCD and PR/SM panels. Once you have defined an LP to be a coupling facility, only the coupling facility control code can run in that LP. When you activate the coupling facility LP, the system automatically loads the CFCC from the support element (an internal laptop) of the CPC.
Implementing a coupling facility in your sysplex requires both hardware and software:
- CPC that supports the CFCC.
- CPCs on which one or more z/OS images run and which are capable of connecting to the coupling facility with CF links.
- Appropriate level of z/OS that allows an exploiter to access a desired function when managing the coupling facility resources.
- CFCC must implement the functions the exploiter needs.
CF – Coupling Facility
CFCC – Coupling Facility Control Code
CPC – Central Processor Complex
HCD – Hardware Configuration Definition
LP – Logical Partition
PR/SM – Processor Resource/System Manager
XES – Cross-system Extended Services