UPAD Exit Routine for User Processing

VSAM calls the UPAD routine only when the request's RPL specifies OPTCD=(SYN, WAITX) and the ACB specifies MACRF=LSR or MACRF=GSR, or MACRF=ICI. VSAM CLOSE can also cause a UPAD exit to be taken to post a record-management request deferred for VSAM internal resource. VSAM takes the UPAD exit to wait for I/O completion or for a serially reusable resource and the UPAD can also be taken to do the corresponding post processing subject to conditions listed in Table 1.

If you are executing in cross-memory mode, you must have a UPAD routine and RPL must specify WAITX.z/OS MVS Programming: Extended Addressability Guide describes cross-memory mode. The UPAD routine is optional for non-cross-memory mode.

Table 1 describes the conditions in which VSAM calls the UPAD routine for synchronous requests with shared resources. UPAD routine exits are taken only for synchronous requests with shared resources or improved control interval processing (ICI).

Table 1. Conditions when exits to UPAD routines are taken
XMM	Sup. state	UPAD needed	I/O wait	I/O post	Resource wait	Resource post
Yes	Yes	Yes	UPAD taken	UPAD taken	UPAD taken	UPAD taken
No	Yes	No	UPAD taken if requested	UPAD not taken even if requested	UPAD taken if requested	UPAD taken if either resource owner or the deferred request runs in XM mode
No	No	No	UPAD taken if requested	UPAD not taken even if requested	UPAD taken if requested	UPAD taken if either resource owner or the deferred request runs in XM mode
Note: You must be in supervisor state when you are in cross-memory mode or SRB mode. RPL WAITX is required if UPAD is required. A UPAD routine can be taken only if RPL specifies WAITX. VSAM gives control to the UPAD exit in the same primary address space of the VSAM record management request. However, VSAM can give control to UPAD with home and secondary ASIDs different from those of the VSAM record management request because the exit was set up during OPEN. When a UPAD exit is taken to do post processing, make sure the ECB is marked posted before returning to VSAM. VSAM does not check the UPAD return code and does not do post after UPAD has been taken. For non-cross-memory task mode only, if the UPAD exit taken for wait returns with ECB not posted, VSAM issues a WAIT SVC. The UPAD exit must return to VSAM in the same address space, mode, state, and addressing mode, and under the same TCB or SRB from which the UPAD exit was called. Registers 1, 13, and 14 must be restored before the UPAD exit returns to VSAM. ICI does not require UPAD for any mode. Resource wait and post processings do not apply to ICI.

RLS ignores the UPAD exit.