Data control block—common fields

Offset	Bytes in Length	Field Name	Description
26(1A)	2	DCBDSORG	Data set organization.
			Code
		1000 000x	IS Indexed sequential.
		0100 000x	PS Physical sequential.
		0010 000x	DA Direct organization.
		...x xx..	Reserved bits.
		0000 001x	PO Partitioned organization.
		.... ...1	U Unmovable—the data set contains location-dependent information.
40(28)	8	DCBDDNAM	Eight-byte name of the data definition statement that defines the data set associated with this DCB. (Before DCB is opened.)
40(28)	2	DCBTIOT	(After DCB is opened.) Offset from the TIOT origin to the TIOELNGH field in the TIOT entry for the DD statement associated with this DCB. Unsigned. Maximum value is just below 64K.
42(2A)	2	DCBMACRF	This field can only be referred to during and after OPEN. It is common to all uses of the DCB and is created by moving the DCBMACR field into this area.
45(2D)	3	DCBDEBA	(After DCB is opened.) Address of field, DEBBASIC, in the associated DEB.
48(30)	1	DCBOFLGS	Flags used by open routine.
		...1 ....	OPEN has completed successfully.
		.... 1...	Set to 1 by problem program to indicate concatenation of unlike attributes.
		.... ..0.	Set to 0 by an I/O support function when that function takes a user exit. It is set to 0 to inhibit other I/O support functions from processing this DCB.
		.... ..1.	Set to 1 on return from the I/O support function that took the exit.
50(32)	2	DCBMACR (Before OPEN)	Macro reference before OPEN. Major macros and various options associated with them. Used by the open routine to determine access method. Used by the access method executed with other parameters to determine which load modules are required. This field is moved to overlay part of DCBDDNAM at OPEN time and becomes the DCBMACRF field. This field is common to all uses of the DCB, but each access method must be referenced for its meaning. For EXCP, bit 0 is always on. If not EXCP, then bit 0 is off and exactly one of the next two bits is on.