Subsystem early code - EQQINIT0

Each z/OS subsystem builds a subsystem vector table (SSVT) control block that defines what functions are supported by that subsystem. The HCL Workload Automation for Z SSVT is built by a separate module, EQQINIT0, which is invoked during the master scheduler initialization at IPL. EQQINIT0 does the following:
  • Sets the UPSS bit in the (SSVT) so that HCL Workload Automation for Z can be started under JES
  • Builds common storage area (CSA) control blocks to queue events until HCL Workload Automation for Z is started
  • Builds a subsystem extension (SSX) block and chains it to the SSVT
  • Builds an SSVT and chains it to the subsystem communication vector table (SSCVT).
The SSVT that EQQINIT0 builds specifies that HCL Workload Automation for Z supports two subsystem calls:
  • A request for service from an HCL Workload Automation for Z dialog (type 67)
  • A notification about a tracking event (type 68).

The code that is required to support these two subsystem calls is contained in a separate load module, EQQSSCM0 . This module is loaded in ECSA by EQQINIT0 processing at IPL. It can be temporarily replaced when the HCL Workload Automation for Z address space is started using the SSCMNAME keyword of OPCOPTS, see Customization and Tuning.