This section describes the SAA Communications and Resource Recovery interfaces.
When an application issues an SAA Communications call, control passes via the DFHCPLC application link-edit stub to the common programming interface program (DFHCPI), which in turn passes the request to the DFHCPIC program load module. DFHCPIC verifies the parameters, checks the conversation state, and (if required) issues a DFHLUC macro call to invoke the LU6.2 application request logic module (DFHZARL). For details of DFHZARL, see Distributed transaction processing.
Figure 72 shows how the SAA Communications interface support relates to CICS® intersystem communication (ISC) using VTAM® LU6.2. The numbers in Figure 72 refer to the notes that follow it. CMxxxx represents a program call defined in the SAA Communications interface.
When using the SAA Communications interface on recoverable conversations (that is, conversations with the synclevel set to CM_SYNC_POINT), DFHLUC syncpoint requests are routed to DFHZARL via the SAA Communications interface syncpoint request handler (DFHCPSRH) in the DFHCPIC load module. This allows the conversation state to be tracked.
For the equivalent EXEC CICS synclevel 2 conversations, DFHLUC syncpoint requests pass directly to DFHZARL.
When an application issues an SAA Resource Recovery call, control passes via the DFHCPLRR application link-edit stub to the common programming interface program (DFHCPI), which in turn passes the request to the DFHCPIRR program load module. DFHCPIRR verifies the parameters, and (if required) issues an appropriate DFHSP macro call: DFHSP TYPE=USER for SRRCMIT, or DFHSP TYPE=ROLLBACK for SRRBACK.
Figure 73 shows how the SAA Resource Recovery interface support relates to the processing of EXEC CICS SYNCPOINT commands. The number in the figure refers to the accompanying note. SRRxxxx represents a program call defined in the SAA Resource Recovery interface, namely, SRRBACK or SRRCMIT.