BMC subsystems

AR/CTL products use BMC standard subsystems for resource management. A major advantage of using subsystem architecture is that it reduces virtual storage requirements in user address spaces.

AR/CTL products use the following two BMC subsystems:

• BMC Primary Subsystem (BMCP)
• BMC Consolidated Subsystem (BCSS)

See Customizing-after-installation for installation of the subsystems. For more information about the subsystems, see Administering.

BMCP

The BMCP establishes supervisory services for the BCSS and many BMC products. It allows interception of open, close, attach, and link requests in the system (AR/CTL enhanced processing is used for interception of enqueue and dequeue requests for remote VSAM access in AR/CTL for VSAM).

BMC products share the BMCP; only one copy of the BMCP may be active on a z/OS system. All associated BMC products continue to operate normally even if the BMCP terminates. However, BMC recommends that you leave the BMCP running at all times.

BCSS

The BCSS manages I/O to the registration data sets (collectively called the REGISET), manages APF-authorized functions, and performs processing for intercepted open, close, attach, and link requests.

The BCSS must be active on the z/OS system where you want to:

• Execute application programs that use AR/CTL products
• Access records in the REGISET through the ISPF interface

More than one BCSS can be active on a z/OS system. One BCSS must be defined as the public BCSS; typically, it is used for production work. Each of the other BCSS is defined as a private BCSS; typically, a private BCSS is used for testing new releases of AR/CTL products. A default BCSS can be designated for all AR/CTL products on each z/OS. You use the BCSS identifier (BCSID) to identify the subsystem (and REGISET) you want to use.

The following three AR/CTL components are available with the BCSS:

• IMS component
• Non IMS component
• VSAM component

The non IMS component must be enabled to allow AR/CTL for Db2 and AR/CTL for VSAM to operate. The IMS component must be enabled to allow AR/CTL for IMS and the BCF component to operate. The VSAM component must be enabled to allow AR/CTL for VSAM to perform logging and dynamic backout of VSAM updates.

You can use the AR/CTL Status Check utility (program AESUVBCS) to ensure that required AR/CTL products, components, and functions are available for application program execution.