An application in a XCF context is a program that has various functions distributed across z/OS systems in a multisystem environment. An application or subsystem might consist of multiple instances, each running on a different system in the same sysplex. Typically, each instance performs certain functions for the application as a whole. Alternatively, each instance could perform all the application’s functions on a given system.
XCF services are available to authorized applications, such as subsystems and z/OS components, to use sysplex services.
XCF – Cross-system Coupling Facility