Using the CICS BAC PLTPI program

About this task

You can use the CICS BAC command processor program, CBKCMNDS, to start CICS BAC during CICS® region initialization. To do this, add an entry to the CICS region PLTPI table. Figure 1 shows a partial DFHPLT table containing the DFHDELIM and CBKCMNDS entries.

Figure 1. DFHPLT entry for starting CICS BAC during CICS initialization
DFHPLT TYPE=ENTRY,PROGRAM=DFHDELIM
DFHPLT TYPE=ENTRY,PROGRAM=CBKCMNDS 

As shown in Figure 1, ensure you add the statement for CBKCMNDS immediately after the DFHDELIM statement. This ensures it executes before any programs that could otherwise attempt to use resources whose state can be altered by CICS BAC startup processing.

The CICS BAC SCBKSAMP data set member, CBKPLTPI, contains a sample PLTPI member.

If you choose to use the PLTPI to activate CICS BAC, you can pass the CICSSTARTMODE parameter to CBKCMNDS for the startup process using the CICS INITPARM system initialization parameter. The following is an example of an INITPARM system initialization parameter for CBKCMNDS:

INITPARM=(CBKCMNDS='CICSSTARTMODE(UPDATE)')

The CICSSTARTMODE parameter is described fully under CICS region commands for CICS BAC. Note that if you omit the INITPARM system initialization option, the CICSSTARTMODE parameter defaults to CICSSTARTMODE(SET) when you start CICS BAC using the PLTPI program. Under the SET option, startup processing reads the records of all resources defined in the region control file and applies their last requested state to the installed CICS resource definitions. As CICS BAC sets each required state in the CICS region, it updates the region control file with information indicating that the state has been set in the CICS region. This action is safe when CICS BAC starts during the PLTPI processing phase, and by the time control is given to CICS, all installed CICS resources that are defined in the region control file are set to their last known state.