IGGPRE00_EXIT and IGGPOST0_EXIT dynamic exits, exit routine Parameter List

Register 1 contains the address of the DADSM preprocessing or postprocessing exit parameter list, obtained from storage below the 16MB line. The IECIEXPL macro maps the parameter list shown in Table 1:

Table 1. IGGPRE00, IGGPOST0 Parameter List. Mapped by IECIEXPL.
Offset	Length or Bit Pattern	Name	Description
00 (X'00')	4	IEXID	ID = 'IEPL'
04 (X'04')	1	IEXLENG	Length of parameter list
05 (X'05')	1	IEXFUNC	DADSM function code
	0000 0111	IEXVEXT	Extend (VSAM caller without DEB parameter). If IEXVEXT is on, you must ensure that your exit routines do not attempt to use the IEXPTR2 field (DEB address is undefined for the extend function).
	0000 0110	IEXPREL	PARTREL partial release
	0000 0101	IEXREN	Rename
	0000 0100	IEXPR	Partial release
	0000 0011	IEXSCR	Scratch
	0000 0010	IEXEXT	Extend
	0000 0001	IEXALL	Create (allocate)
06 (X'06')	1	IEXEXTCD	Extend code
	1000 0001		Extend VSAM data set on current volume
	0000 0100		Extend non-VSAM data set on new volume
	0000 0001		Extend non-VSAM data set on current volume
07 (X'07')	1	IEXFLAG	Flag byte
	1... ....	IEXENQ	VTOC is enqueued upon entry
	.1.. ....	IEXVIO	VIO data set
	..1. ....	IEXMF1	IEXFMT1 points to PD1FMTID of a partial format-1 DSCB (partial DSCB passed as input to allocate, and JFCB is not available)
	...1 ....	IEXFDSCB	Full format-1 DSCB (ALLOC=ABS)
	.... xxx.	IEXAVGR	Average record value. These bits apply only to the allocate function (IEXALL) with the JFCB specified (IEXPTR1). At most, one of these three bits might be on. If all are zero, this is not an average record space request.
	.... 1...	IEXAVGRU	Average record space request. Multiply JFCBPQTY and JFCBDRLH to get requested primary space in bytes. Multiply JFCBSQTY and JFCBDRLH to get requested secondary space in bytes.
	.... .1..	IEXAVGRK	Average record space request. Multiply JFCBPQTY, JFCBDRLH, and 1024 to get requested primary space in bytes. Multiply JFCBSQTY, JFCBDRLH, and 1024 to get requested secondary space in bytes.
	.... ..1.	IEXAVGRM	Average record space request. Multiply JFCBPQTY, JFCBDRLH, and 1,048,576 to get requested primary space in bytes. Multiply JFCBSQTY, JFCBDRLH, and 1,048,576 to get requested secondary space in bytes.
	.... ...1	IEXFEDT2	Extent descriptor table 2 (pointed to by IEXEDT2) contains valid extent information. This bit is always on for pre- and postexit for scratch and partial release and postexit for create and extend. If you want your exit also to run on earlier systems that do not have an extent descriptor table 2, then IBM recommends this logic for non-VIO data sets: If IEXFEDT2 is on, then use IEXEDT2, otherwise use IEXEDT1.
08 (X'08')	2	IEXREASN	Installation reject reason code
10 (X'0A')	BIT(8)	IEXDSFLG	Data set indicators
	111. ....	*	RESERVED
	...1 ....	IEXCOMPR	Compressable extended
	.... 1...	IEXPDSE	PDSE data set
	.... .1..	IEXSTRP	Extended format data set
	.... ..1.	IEXPDSEX	HFS data set
	.... ...1	IEXVSAM	VSAM data set
11 (X'0B')	1	IEXNUMF9	Number of contiguous format 9 DSCBs at the IEXFMT9 storage address that is provided by the pre-exit for create. In z/OS V1R10, the values of zero and one are valid.
12 (X'0C')	4	IEXUCB	Address of the UCB. It will be an actual 31–bit UCB address above or below the 16MB line. The UCB address is not available to the pre-exit for VIO allocation.
16 (X'10')	4	IEXPTR1	Address of one of the following: JFCB or a copy of the JFCB (create, extend, partial release) Data set name (PARTREL partial release) Scratch or rename parameter list (See z/OS DFSMSdfp Advanced Services for a description of the scratch or rename parameter list.) When the scheduler work area (SWA) resides above the 16MB line, you might have to modify the exit routine references to the IEXPTR1 field. See Characteristics of the IGGPRE00_EXIT and IGGPOST0_EXIT Exit Dynamic Exits, Exit Routines for further information.
20 (X'14')	4	IEXPTR2	Address of one of the following: DEB (extend on old volume) DCB (partial release entered by CLOSE). Partial DCB (PARTREL partial release, caller is VSAM). DCBFDAD and DCBDEBA are defined, the associated DEB has been constructed; DEBDSCBA, DEBNMEXT, and the DEBDASD segments are defined. DEBDVMOD is not defined. Current volume list entry (scratch, rename)
24 (X'18')	4	IEXDSN	Address of the data set name
28 (X'1C')	4	IEXFMT1	Address of the 96-byte data portion of the format-1 DSCB (pre-exit for scratch; pre- and post-exit for partial release and rename; post-exit for create). Might be supplied by pre-exit of create, and extend on new volume, to serve as a model if IEXMF1 and IEXVIO are zero. The format-1 DSCB is mapped by the IECSDSL1 macro. You can find the fields in z/OS DFSMSdfp Advanced Services.For large format data sets, unique bit settings in fields DS1FLAG1 and DS1LSTAR may need to be examined.
32 (X'20')	4	IEXFMT9	Storage address of a format 9 DSCB model. Pre-exit and post-exit for create. Might be supplied by the pre-exit for create to serve as a model if IEXMF1 is zero. Allows the pre-exit to alter the contents of the following fields: DS9ATRI1, DS9ATRV1. DS9ATRI1 and DS9ATRI2 may contain reserved fields. The values in the remaining fields will have no effect. The exit should leave reserved fields as binary zeroes to prevent them from updating the real DSCB when IBM defines new fields in future releases.
36 (X'24')	4	IEXFMT3	Address of the format-3 DSCB (ALLOC=ABS)
40 (X'28')	4	IEXEDT1, IEXEXTBL	Address of extent descriptor table 1 with 2-byte relative track addresses (pre- and postexit for scratch and partial release; postexit for create and extend). For the VIO create post-exit, this is the address of DS1EXT1 in the virtual format-1 DSCB (IEXEDT1 is a synonym for IEXEXTBL). If the volume capacity is more than 65,535 tracks, then this table does not contain extent information. There is no mapping macro for this table. This extent descriptor table is provided for coexistence with previous releases of the system. See the descriptions of IEXFEDT2 and IEXEDT2.
44 (X'2C')	4	IEXDCC	DADSM return code (post-exit only). The return code from the called DADSM function is put here.
48 (X'30')	4	IEXRSVWD	Reserved word for use by exit routine
52 (X'34')	4	IEXEDT2	Address of extent descriptor table 2 with 4-byte relative track addresses (pre- and postexit for scratch and partial release; postexit for create and extend). Macro ICVEDT02 maps this table. The format of this table is described in z/OS DFSMSdfp Advanced Services. For VIO create postexit, IEXEDT2 is the address of DS1EXT1 in the virtual format-1 DSCB. Also see bit IEXFEDT2.