Coupling facilities

A coupling facility provides locking, caching, and list services between coupling-capable z/OS® processors. Coupling-facility links connect a coupling facility to the coupling-capable processors. The coupling-facility control code (CFCC) provides the coupling-facility functions. The CFCC can run in a processor resource/systems manager (PR/SM) logical partition (LP) in the following processors
  • IBM Enterprise System/9000 (ES/9000) 9021 711-based processor
  • An IBM S/390 Parallel Enterprise Server 9672 (IBM 9672)
  • An IBM S/390® coupling facility 9674 (IBM 9674)

You can use the Integrated Coupling Migration Facility (ICMF) for migration and for testing software that requires a coupling facility. ICMF provides the CFCC functions without coupling-facility links and is limited to z/OS systems that run in an LP on a single physical system. ICMF is available on the 9021 711-based processors, 9121 511-based processors, and IBM 9672s.

A coupling facility enables software on different systems in the Parallel Sysplex® to share data with the assurance that the data will not be corrupted and will be consistent among all sharing users. To share data, systems must have connectivity to the coupling facility through coupling-facility links.

DFSMStvs is one of many exploiters of coupling facilities. You might already have coupling facilities in use for one or more of these functions:
  • Enhanced catalog sharing
  • Tape drive sharing
  • JES2 checkpoint
  • Operator log
  • Global resource serialization
  • VTAM® generic resources
  • SmartPipes
  • Resource recovery services (RRS)
  • CICS® logs, temporary storage, and data tables
  • DB2® locks and buffer pools
  • IMS short message queue, locks and buffer pools
  • VSAM record-level sharing (RLS) for caching and locking

Requirement: You must have at least CF level 2 microcode installed before using DFSMStvs.