Subzero controlling agent

• Communicates with DBC
• Communicates with other Subzero controlling agents
• If internally designated as the master, communicates with LGC to obtain current Subzero configuration values, and shares them with other Subzero controlling agents

• Automatically interfaces with clients on this LPAR as needed, based on the defined configuration values

  If configuration values define any potential clients on this LPAR, the controlling agent prepares to redirect subsystem access requests to the appropriate target subsystem on a remote LPAR. The controlling agent serves all clients on this LPAR.

  The controlling agent establishes a Subzero cross-memory environment and cross-system coupling facility (XCF) communication between the client address space and the remote subsystem, as follows:

  • Creates a reusable linkage index (LX) within the client address space
  • Allocates approximately 250 KB in the extended common service area (ECSA) for executable cross-memory routines, and approximately 4 MB of 64-bit common memory objects for XCF message buffers

  Note

  After establishing the communications environment, the controlling agent is no longer involved in redirection; therefore, it consumes minimal CPU resources. The controlling agent terminates automatically when it is no longer needed.

• Automatically starts and stops Subzero subsystem servers as needed, when a controlling agent on a client LPAR requests access to a subsystem that is participating in redirection

DBC starts the controlling agent automatically as a separate address space. The controlling agent runs as an external agent under the control of DBC. The default address space job name of a controlling agent is BRDCNTL. All of the Subzero controlling agents that are running on the different LPARs in the sysplex communicate with each other.

Subzero controlling agents and subsystem servers share a common code base, simplifying operations and maintenance.