Control Blocks

DSECT Function
DFHSABDS The CICS® subsystem anchor block (SAB). This is used to contain global subsystem-related information that is common to all CICS regions in the MVS™ image. It is used to record the options specified in the DFHSSInn member of SYS1.PARMLIB. It contains a pointer to a bit map that records which MVS address spaces contain an active CICS. It also contains the address of the subsystem control table extension (SCTE) used by IRC, and the address of the CEC status tracking information used by XRF.
IEFJSCVT The subsystem communication table (SSCT). This is an MVS control block. There is one SSCT for each subsystem, including the primary job entry subsystem (JES) as well as CICS.
IEFJSSVT The subsystem vector table (SSVT). This is an MVS control block. There is one SSVT for each active subsystem. It contains a lookup table for determining which function codes are supported by the subsystem, and a list of the entry points for all the supporting function routines.

Figure 74 shows these control blocks.

Figure 74. Control blocks associated with the subsystem interface
 This is a technical drawing showing the control blocks listed in the table, and their relationships to each other.
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