Establishing addressability for function calls

Because QMF always branches to an entry point named DSQUnGV1 (TSO, ISPF, or native z/OS®) or DSQUnGV3 (CICS®) when it calls the governor, you cannot use these entry points to determine the type of function call; instead, use the GOVFUNCT field of the DXEGOVA control block.

In the IBM-supplied governor exit routine, GOVFUNCT contains a character value that identifies the type of function call. This character value, in turn, equates to a 1-byte binary integer from 1 to 10. For example, on a function call for the start of a QMF session, the value of GOVFUNCT is GOVINIT, which equates to a numeric value of X'1'.

Both character and numeric values for each type of function call are shown in this figure. GOVABEND is not called when running in CICS.

Figure 1. Character and numeric values for the GOVFUNCT field of the DXEGOVA control block

GOVINIT  EQU   1             -------- INITIALIZATION OF SESSION
GOVTERM  EQU   2             -------- TERMINATION OF SESSION
GOVSCMD  EQU   3             -------- START COMMAND
GOVECMD  EQU   4             -------- END COMMAND
GOVCONN  EQU   5             -------- CONNECT COMMAND
GOVSDBAS EQU   6             -------- START DATABASE
GOVEDBAS EQU   7             -------- END DATABASE
GOVSACTV EQU   8             -------- SUSPEND QMF ACTIVITY
GOVRACTV EQU   9             -------- RESUME QMF ACTIVITY
GOVABEND EQU   10            -------- QMF ABEND OPERATION

To improve performance in your own exit routine, you can follow the convention the IBM-supplied governor uses, and equate the values of GOVFUNCT with binary numbers by using a branch table. QMF uses the branch table to find the addresses to branch to for each type of function call.

The following example code identifies branch addresses for the default governor.

Figure 2. Identifying the type of function call and branching to the appropriate address

XR    R07,R07               ZERO REGISTER 7
         IC    R07,GOVFUNCT          IDENTIFY EXIT TYPE
         SLL   R07,2                 DETERMINE BRANCH TABLE OFFSET
         LA    R15,FUNBTAB(R07)      GET BRANCH TABLE ADDRESS
         L     R15,0(R15)            GET BRANCHING ADDRESS
         BALR  R14,R15               BRANCH TO THE APPROPRIATE CODE
            . . .
            . . .
            . . .
            . . .
FUNBTAB  DS    0F
         DC    A(BYPASS)          VALUE "0"  - UNUSED
         DC    A(INIT)            VALUE "1"  - QMF INITIALIZATION
            . . .
            . . .
            . . .
         DC    A(SUSPEND)         VALUE "10" - QMF ABEND IN PROCESS