DCB for ISAM

Common Name:

Data Control Block for ISAM

Macro ID:

DCBD

DSECT Name:

IHADCB

Owning Component:

Data Management, subcomponent OPEN/CLOSE/EOV

Eye-Catcher ID:

None

Subpool and Key:

Problem program subpool and key

Size:

252 bytes

Created by:

Problem program

Pointed to by:

DEBDCBAD field of the DEB data area
IOBDCBPT field of the IOB data area
DECDCBAD field of the DECB data area

Serialization:

None — DEB validity check ensures the contents of this DCB.

Function:

The system no longer supports the indexed sequential access method (ISAM). Instead, VSAM emulates ISAM. This data control block (DCB) is used by the VSAM routines that emulate ISAM and holds data pertinent to the use of a data set that is maintained by these routines. VSAM does not maintain all of the fields in this DCB. The common interface and the foundation sections serve the same purpose in all DCBs, although the format might vary slightly for each access method routine.

Offset	Type/Value	Len	Name (Dim)	Description
DATA CONTROL BLOCK DEFINITION
	X'80'		DCBBIT0	"128"
	X'40'		DCBBIT1	"64"
	X'20'		DCBBIT2	"32"
	X'10'		DCBBIT3	"16"
	X'8'		DCBBIT4	"8"
	X'4'		DCBBIT5	"4"
	X'2'		DCBBIT6	"2"
	X'1'		DCBBIT7	"1"
ACCESS METHOD COMMON INTERFACE
16 (10)	SIGNED	4	DCBRELB(0)	– SAME AS DCBREL BELOW
16 (10)	SIGNED	1	DCBKEYLE	– KEY LENGTH OF DATA SET
17 (11)	CHARACTER	1	DCBDEVT(0)	– DEVICE TYPE
	.1. . 1111		DCBDVTRM	"X'4F'"– TERMINAL. (DD CONTAINS TERM=TS)
17 (11)	SIGNED	3	DCBREL	– NUMBER OF RELATIVE TRACKS OR BLOCKS IN THIS DATA SET (BDAM)
20 (14)	ADDRESS	4	DCBBUFCB(0)	– ADDRESS OF BUFFER POOL CONTROL BLOCK
20 (14)	SIGNED	1	DCBBUFNO	– NUMBER OF BUFFERS REQUIRED FOR THIS DATA SET. MAY RANGE FROM 0 TO 255. IF UNBLOCKED SPANNED RECORDS ARE USED, NUMBER OF SEGMENT WORK AREAS REQUIRED FOR THIS DATA SET.
21 (15)	ADDRESS	3	DCBBUFCA	– ADDRESS OF BUFFER POOL CONTROL BLOCK
24 (18)	SIGNED	2	DCBBUFL	– LENGTH OF BUFFER. MAY RANGE FROM 0 TO 32,767.
26 (1A)	BITSTRING	2	DCBDSORG(0)	– DATA SET ORGANIZATION BEING USED
26 (1A)	BITSTRING	1	DCBDSRG1	– FIRST BYTE OF DCBDSORG
	1. . . . . . .		DCBDSGIS	"DCBBIT0"– IS – INDEXED SEQUENTIAL ORGANIZATION
	.1. . . . . .		DCBDSGPS	"DCBBIT1"– PS – PHYSICAL SEQUENTIAL ORGANIZATION
	. .1. . . . .		DCBDSGDA	"DCBBIT2"– DA – DIRECT ORGANIZATION
	. . .1 . . . .		DCBDSGCX	"DCBBIT3"– CX – BTAM OR QTAM LINE GROUP
	. . . . . .1.		DCBDSGPO	"DCBBIT6"– PO – PARTITIONED ORGANIZATION
	. . . . . . .1		DCBDSGU	"DCBBIT7"– U – UNMOVABLE, THE DATA CONTAINS LOCATION DEPENDENT INFORMATION
27 (1B)	BITSTRING	1	DCBDSRG2	– SECOND BYTE OF DCBDSORG
	1. . . . . . .		DCBDSGGS	"DCBBIT0"– GS – GRAPHICS ORGANIZATION
	.1. . . . . .		DCBDSGTX	RESERVED
	. .1. . . . .		DCBDSGTQ	RESERVED
	. . . . 1. . .		DCBACBM	"DCBBIT4"– ACCESS METHOD CONTROL BLOCK
	. . . . .1. .		DCBDSGTR	RESERVED
28 (1C)	ADDRESS	4	DCBIOBAD(0)	ADDRRESS OF IOB.
28 (1C)	ADDRESS	4	DCBICQE(0)	– ADDRESS OF ICQE
28 (1C)	ADDRESS	4	DCBODEB(0)	– ADDRESS OF OLD DEB
28 (1C)	SIGNED	1	DCBLNP(0)	– 3525 PRINTER LINE POSITION COUNTER
28 (1C)	BITSTRING	1	DCBQSLM	– QSAM LOCATE MODE LOGICAL RECORD INTERFACE INDICATOR BYTE FOR UPDATE PROCESSING OF SPANNED RECORDS
	1. . . . . . .		DCB1DVDS	"DCBBIT0"– ONLY ONE DEVICE IS ALLOCATED TO THIS DATA SET
	.1. . . . . .		DCBUPDCM	"DCBBIT1"– UPDATE COMPLETE, FREE OLD DEB
	. .11 . . . .		DCBUPDBT	"DCBBIT2+DCBBIT3"– UPDATE BITS
	. .1. . . . .		DCBUPDT	"DCBBIT2"– UPDATE TO TAKE PLACE
	. .11 . . . .		DCBNUPD	"DCBBIT2+DCBBIT3"– NO UPDATE TO TAKE PLACE
	. . .1 . . . .		DCBSVDEB	"DCBBIT3"– OLD DEB ADDRESS MUST BE SAVED
29 (1D)	ADDRESS	3	DCBIOBAA(0)	– SAME AS DCBIOBAD ABOVE
29 (1D)	ADDRESS	3	DCBICQEA(0)	– SAME AS DCBICQE ABOVE
29 (1D)	ADDRESS	3	DCBODEBA	–ADDRESS OF OLD DEB
28 (1C)	ADDRESS	4	DCBSVCXL(0)	–SAME AS DCBSVCXA BELOW
28 (1C)	BITSTRING	1		– RESERVED
29 (1D)	ADDRESS	3	DCBSVCXA	– POINTER TO EXIT LIST OF JES C.I. INTERFACE CONTROL SVC
FOUNDATION EXTENSION
32 (20)	ADDRESS	4	DCBEODAD(0)	– SAME AS DCBEODA BELOW
32 (20)	BITSTRING	1	DCBHIARC(0)	– HIERARCHY BITS
32 (20)	BITSTRING	1	DCBBFTEK(0)	– BUFFERING TECHNIQUE BITS
32 (20)	BITSTRING	1	DCBBFALN	– BUFFER ALIGNMENT BITS
	1. . . . . . .		DCBH1	"DCBBIT0"– HIERARCHY 1 MAIN STORAGE – BIT 5 IS ZERO
	.111 . . . .		DCBBFT	"DCBBIT1+DCBBIT2+DCBBIT3" BUFFERING TECHNIQUE
	.11. . . . .		DCBBFTA	"DCBBIT1+DCBBIT2"– QSAM LOCATE MODE PROCESSING OF SPANNED RECORDS – OPEN IS TO CONSTRUCT A RECORD AREA IF IT AUTOMATICALLY CONSTRUCTS BUFFERS
	. .1. . . . .		DCBBFTR	"DCBBIT2"– FOR BSAM CREATE BDAM PROCESSING OF UNBLOCKED SPANNED RECORDS – SOFTWARE TRACK OVERFLOW. FOR BSAM INPUT PROCESSING OF UNBLOCKED SPANNED RECORDS WITH KEYS – RECORD OFFSET PROCESSING.
	.1. . . . . .		DCBBFTS	"DCBBIT1"– SIMPLE BUFFERING – BIT 3 IS ZERO
	. .1. . . . .		DCBBFTKR	"DCBBIT2"– UNBLOCKED SPANNED RECORDS – SOFTWARE TRACK OVERFLOW (BDAM)
	. . .1 . . . .		DCBBFTE	"DCBBIT3"– EXCHANGE BUFFERING – BIT 1 IS ZERO
	. . . . 1. . .		DCBBFTKD	"DCBBIT4"– DYNAMIC BUFFERING (BTAM)
	. . . . 1. . .		DCBBFTK	"DCBBIT4"– LRECL IN 'K' UNITS FOR XLRI
	.11. 1. . .		DCBBXLRI	"DCBBIT1+DCBBIT2+DCBBIT4"– EXTENDED LOGICAL RECORD INTERFACE MODE FOR SPANNED RECORDS GREATER THAN 32K – ALL RECORDS TRANSFERRED TO OR FROM THE RECORD AREA.
	. . . . .1. .		DCBH0	"DCBBIT5"– HIERARCHY 0 MAIN STORAGE – BIT 0 IS ZERO
	. . . . . .11		DCBBFA	"DCBBIT6+DCBBIT7"– BUFFER ALIGNMENT
	. . . . . .1.		DCBBFAD	"DCBBIT6"– DOUBLEWORD BOUNDARY
	. . . . . . .1		DCBBFAF1	"DCBBIT7"– FULLWORD NOT A DOUBLEWORD BOUNDARY, CODED IN DCB MACRO INSTRUCTION
	. . . . . .11		DCBBFAF2	"DCBBIT6+DCBBIT7"– FULLWORD NOT A DOUBLEWORD BOUNDARY, CODED IN DCB MACRO INSTRUCTION
33 (21)	ADDRESS	3	DCBEODA	– ADDRESS OF A USER– PROVIDED ROUTINE TO HANDLE END-OF-DATA CONDITIONS
36 (24)	ADDRESS	4	DCBEXLST(0)	– ADDRESS OF USER– PROVIDED LIST OF EXITS
36 (24)	BITSTRING	1	DCBRECFM	– RECORD FORMAT
	111. . . . .		DCBRECLA	"DCBBIT0+DCBBIT1+DCBBIT2" RECORD LENGTH INDICATOR –ASCII
	. .1. . . . .		DCBRECD	"DCBBIT2"– ASCII VARIABLE RECORD LENGTH
	11. . . . . .		DCBRECL	"DCBBIT0+DCBBIT1"– RECORD LENGTH INDICATOR
	1. . . . . . .		DCBRECF	"DCBBIT0"–FIXED RECORD LENGTH
	.1. . . . . .		DCBRECV	"DCBBIT1"– VARIABLE RECORD LENGTH
	11. . . . . .		DCBRECU	"DCBBIT0+DCBBIT1"– UNDEFINED RECORD LENGTH
	. .1. . . . .		DCBRECTO	"DCBBIT2"– TRACK OVERFLOW
	. . .1 . . . .		DCBRECBR	"DCBBIT3"– BLOCKED RECORDS
	. . . . 1. . .		DCBRECSB	"DCBBIT4"– FOR FIXED LENGTH RECORD FORMAT – STANDARD BLOCKS. FOR VARIABLE LENGTH RECORD FORMAT – SPANNED RECORDS
	. . . . .11.		DCBRECCC	"DCBBIT5+DCBBIT6"– CONTROL CHARACTER INDICATOR
	. . . . .1. .		DCBRECCA	"DCBBIT5"– ASA CONTROL CHARACTER
	. . . . . .1.		DCBRECCM	"DCBBIT6"– MACHINE CONTROL CHARACTER
	. . . . . . . .		DCBRECC	"X'00'"– NO CONTROL CHARACTER
	. . . . . . .1		DCBRECKL	"DCBBIT7"– KEY LENGTH (KEYLEN) WAS SPECIFIED IN DCB MACRO INSTRUCTION
37 (25)	ADDRESS	3	DCBEXLSA	– ADDRESS OF USER–PROVIDED LIST OF EXITS
FOUNDATION BEFORE OPEN
40 (28)	CHARACTER	8	DCBDDNAM	– NAME ON THE DD STATEMENT THAT DEFINES THE DATA SET ASSOCIATED WITH THIS DCB
48 (30)	BITSTRING	1	DCBOFLGS	– FLAGS USED BY OPEN ROUTINE
	1. . . . . . .		DCBOFLWR	"DCBBIT0"– IF ZERO, LAST I/O OPERATION WAS READ OR POINT. IF ONE, LAST I/O OPERATION WAS WRITE.
	1. . . . . . .		DCBOFIOD	"DCBBIT0"– DATA SET IS BEING OPENED FOR INPUT OR OUTPUT (BDAM)
	.1. . . . . .		DCBOFLRB	"DCBBIT1"– LAST I/O OPERATION WAS IN READ BACKWARD MODE
	. .1. . . . .		DCBOFEOV	"DCBBIT2"– SET TO 1 BY EOV WHEN IT CALLS CLOSE ROUTINE FOR CONCATENATION OF DATA SETS WITH UNLIKE ATTRIBUTES
	. . .1 . . . .		DCBOFOPN	"DCBBIT3"– AN OPEN HAS BEEN SUCCESSFULLY COMPLETED
	. . . . 1. . .		DCBOFPPC	"DCBBIT4"– SET TO 1 BY PROBLEM PROGRAM TO INDICATE A CONCATENATION OF UNLIKE ATTRIBUTES
	. . . . .1. .		DCBOFTM	"DCBBIT5"– TAPE MARK HAS BEEN READ
	. . . . . .1.		DCBOFUEX	"DCBBIT6"– SET TO 0 BY AN I/O SUPPORT FUNCTION WHEN THAT FUNCTION TAKES A USER EXIT. SET TO 1 ON RETURN FROM USER EXIT TO THE I/O SUPPORT FUNCTION WHICH TOOK THE EXIT.
	. . . . . . .1		DCBOFIOF	"DCBBIT7"– 1 BY AN I/O SUPPORT FUNCTION IF DCB IS TO BE PROCESSED BY THAT FUNCTION
49 (31)	BITSTRING	1	DCBIFLG	– FLAGS USED BY IOS IN COMMUNICATING ERROR CONDITIONS AND IN DETERMINING CORRECTIVE PROCEDURES
	11. . . . . .		DCBIBEC	"DCBBIT0+DCBBIT1"– ERROR CORRECTION INDICATOR
	. . . . . . . .		DCBIFNEP	"X'00'"– NOT IN ERROR PROCEDURE
	.1. . . . . .		DCBEX	"DCBBIT1"– ERROR CORRECTION OR IOS PAGE FIX IN PROCESS
	11. . . . . .		DCBIFPEC	"DCBBIT0+DCBBIT1"– PERMANENT ERROR CORRECTION
	. .11 . . . .		DCBIBPCT	"DCBBIT2+DCBBIT3"– PRINTER CARRIAGE TAPE PUNCH INDICATOR
	. .1. . . . .		DCBIFC9	"DCBBIT2"– CHANNEL 9 PRINTER CARRIAGE TAPE PUNCH SENSED
	. . .1 . . . .		DCBIFC12	"DCBBIT3" – CHANNEL 12 PRINTER CARRIAGE TAPE PUNCH SENSED
	. . . . 11. .		DCBIBIOE	"DCBBIT4+DCBBIT5"– IOS ERROR ROUTINE USE INDICATOR
	. . . . . . . .		DCBIFER	"X'00'"– ALWAYS USE I/O SUPERVISOR ERROR ROUTINE
	. . . . .1. .		DCBIFNE1	"DCBBIT5"– NEVER USE I/O SUPERVISOR ERROR ROUTINE
	. . . . .1. .		DCBIFTIM	"DCBBIT5"– TEST IOS MASK (IMSK) FOR ERROR PROCEDURE (BTAM)
	. . . . 1. . .		DCBIFNE2	"DCBBIT4"– NEVER USE I/O SUPERVISOR ERROR ROUTINE
	. . . . 11. .		DCBIFNE3	"DCBBIT4+DCBBIT5"– NEVER USE I/O SUPERVISOR ERROR ROUTINE
50 (32)	BITSTRING	2	DCBMACR(0)	– MACRO INSTRUCTION REFERENCE
50 (32)	BITSTRING	1	DCBMACR1	– FIRST BYTE OF DCBMACR
	1. . . . . . .		DCBMRECP	"DCBBIT0"– EXECUTE CHANNEL PROGRAM (EXCP) – – – ALWAYS ZERO (BSAM, QSAM, BPAM, BISAM, QISAM, BDAM) – – – RESERVED (QTAM, BTAM)
	.1. . . . . .		DCBMRFE	"DCBBIT1"– FOUNDATION EXTENSION IS PRESENT (EXCP)
	.1. . . . . .		DCBMRGET	"DCBBIT1"– GET (QSAM, QISAM)
	.1. . . . . .		DCBMRPTQ	"DCBBIT1"– PUT FOR MESSAGE GROUP (QTAM) – – – ALWAYS ZERO (BSAM, BPAM, BISAM, BDAM) – – – RESERVED (BTAM)
	. .1. . . . .		DCBMRAPG	"DCBBIT2"– APPENDAGES ARE REQUIRED (EXCP)
	. .1. . . . .		DCBMRRD	"DCBBIT2"– READ (BSAM, BPAM, BISAM, BDAM, BTAM)
	. .1. . . . .		DCBMRWRQ	"DCBBIT2"– WRITE FOR LINE GROUP (QTAM) – – – ALWAYS ZERO (QSAM, QISAM)
	. . .1 . . . .		DCBMRCI	"DCBBIT3"– COMMON INTERFACE (EXCP)
	. . .1 . . . .		DCBMRMVG	"DCBBIT3"– MOVE MODE OF GET (QSAM, QISAM)
	. . .1 . . . .		DCBMRRDK	"DCBBIT3"– KEY SEGMENT WITH READ (BDAM) – – – ALWAYS ZERO (BISAM) – – – RESERVED (BSAM, BPAM, QTAM, BTAM)
	. . . . 1. . .		DCBMRLCG	"DCBBIT4"– LOCATE MODE OF GET (QSAM, QISAM)
	. . . . 1. . .		DCBMRRDI	"DCBBIT4"– ID ARGUMENT WITH READ (BDAM) – – – ALWAYS ZERO (BISAM) – – – RESERVED (EXCP, BSAM, BPAM, QTAM, BTAM)
	. . . . .1. .		DCBMRABC	"DCBBIT5"– USER'S PROGRAM MAINTAINS ACCURATE BLOCK COUNT (EXCP)
	. . . . .1. .		DCBMRPT1	"DCBBIT5"– POINT (WHICH IMPLIES NOTE) (BSAM, BPAM)
	. . . . .1. .		DCBMRSBG	"DCBBIT5"– SUBSTITUTE MODE OF GET (QSAM)
	. . . . .1. .		DCBMRDBF	"DCBBIT5"–DYNAMIC BUFFERING (BISAM, BDAM)– – – ALWAYS ZERO (QISAM) – – – RESERVED (QTAM, BTAM)
	. . . . . .1.		DCBPGFXA	"DCBBIT6"– PAGE FIX APPENDAGE IS SPECIFIED (EXCP)
	. . . . . .1.		DCBMRCRL	"DCBBIT6"– CNTRL (BSAM, QSAM)
	. . . . . .1.		DCBMRCHK	"DCBBIT6"– CHECK (BISAM)
	. . . . . .1.		DCBMRRDX	"DCBBIT6"– READ EXCLUSIVE (BDAM) – – – RESERVED (BPAM, QISAM, QTAM, BTAM)
	. . . . . . .1		DCBMRDMG	"DCBBIT7"–DATA MODE OF GET (QSAM)
	. . . . . . .1		DCBMRCK	"DCBBIT7"– CHECK (BDAM) – – – RESERVED (EXCP, BSAM, BPAM, BISAM, QISAM, QTAM, BTAM)
51 (33)	BITSTRING	1	DCBMACR2	– SECOND BYTE OF DCBMACR
	1. . . . . . .		DCBMRSTL	"DCBBIT0"– SETL (QISAM) – – – ALWAYS ZERO (BSAM, QSAM, BPAM, BISAM, BDAM) – – – RESERVED (EXCP, QTAM, BTAM)
	.1. . . . . .		DCBMRPUT	"DCBBIT1"– PUT (QSAM) – PUT OR PUTX (QISAM)
	.1. . . . . .		DCBMRGTQ	"DCBBIT1"– GET FOR MESSAGE GROUP (QTAM) – – –ALWAYS ZERO (BSAM, BPAM, BISAM, BDAM) – – – RESERVED (EXCP, BTAM)
	. .1. . . . .		DCBMRWRT	"DCBBIT2"– WRITE (BSAM, BPAM, BISAM, BDAM, BTAM)
	. .1. . . . .		DCBMRRDQ	"DCBBIT2"– READ FOR LINE GROUP (QTAM) – – – ALWAYS ZERO (QSAM, QISAM) – – – RESERVED (EXCP)
	. . .1 . . . .		DCBMRMVP	"DCBBIT3"– MOVE MODE OF PUT (QSAM, QISAM)
	. . .1 . . . .		DCBMRWRK	"DCBBIT3"– KEY SEGMENT WITH WRITE (BDAM) – – – ALWAYS ZERO (BISAM) – – – RESERVED (EXCP, BSAM, BPAM, QTAM, BTAM)
	. . . . 1. . .		DCBMR5WD	"DCBBIT4"– FIVE-WORD DEVICE INTERFACE (EXCP)
	. . . . 1. . .		DCBMRLDM	"DCBBIT4"– LOAD MODE BSAM (CREATE BDAM DATA SET) (BSAM)
	. . . . 1. . .		DCBMRLCP	"DCBBIT4"– LOCATE MODE OF PUT (QSAM, QISAM)
	. . . . 1. . .		DCBMRIDW	"DCBBIT4"– ID ARGUMENT WITH WRITE (BDAM) – – ALWAYS ZERO (BISAM) – – – RESERVED (BPAM, QTAM, BTAM)
	. . . . .1. .		DCBMR4WD	"DCBBIT5"– FOUR-WORD DEVICE INTERFACE (EXCP)
	. . . . .1. .		DCBMRPT2	"DCBBIT5"– POINT (WHICH IMPLIES NOTE) (BSAM, BPAM)
	. . . . .1. .		DCBMRTMD	"DCBBIT5"– SUBSTITUTE MODE (QSAM)
	. . . . .1. .		DCBMRUIP	"DCBBIT5"– UPDATE IN PLACE (PUTX) (QISAM) – – –ALWAYS ZERO (BISAM) – – – RESERVED (BDAM, QTAM, BTAM)
	. . . . . .1.		DCBMR3WD	"DCBBIT6"– THREE–WORD DEVICE INTERFACE (EXCP)
	. . . . . .1.		DCBMRCTL	"DCBBIT6"– CNTRL (BSAM, QSAM)
	. . . . . .1.		DCBMRSTK	"DCBBIT6"– SETL BY KEY (QISAM)
	. . . . . .1.		DCBMRAWR	"DCBBIT6"– ADD TYPE OF WRITE (BDAM) – – – ALWAYS ZERO (BISAM) – – – RESERVED (BPAM, QTAM, BTAM)
	. . . . . . .1		DCBMR1WD	"DCBBIT7"– ONE–WORD DEVICE INTERFACE (EXCP)
	. . . . . . .1		DCBMRSWA	"DCBBIT7"– USER'S PROGRAM HAS PROVIDED A SEGMENT WORK AREA POOL (BSAM CREATE BDAM, BDAM)
	. . . . . . .1		DCBMRDMD	"DCBBIT7"– DATA MODE (QSAM)
	. . . . . . .1		DCBMRSTI	"DCBBIT7"– SETL BY ID (QISAM) – – – ALWAYS ZERO (BISAM) – – – RESERVED (BPAM, QTAM, BTAM)
FOUNDATION AFTER OPEN
40 (28)	ADDRESS	2	DCBTIOT	OFFSET FROM TIOT ORIGIN TO TIOELNGH FIELD IN TIOT ENTRY FOR DD STATEMENT ASSOCIATED WITH THIS DCB
42 (2A)	BITSTRING	2	DCBMACRF(0)	– SAME AS DCBMACR BEFORE OPEN
42 (2A)	BITSTRING	1	DCBMACF1	– FIRST BYTE OF DCBMACRF
43 (2B)	BITSTRING	1	DCBMACF2	– SECOND BYTE OF DCBMACRF
44 (2C)	ADDRESS	4	DCBDEBAD(0)	– ADDRESS OF ASSOCIATED DEB
44 (2C)	BITSTRING	1	DCBIFLGS	– SAME AS DCBIFLG BEFORE OPEN
	11. . . . . .		DCBIFEC	"DCBBIT0+DCBBIT1"– ERROR CORRECTION INDICATOR
	. .11 . . . .		DCBIFPCT	"DCBBIT2+DCBBIT3"– PRINTER CARRIAGE TAPE PUNCH INDICATOR
	. . . . 11. .		DCBIFIOE	"DCBBIT4+DCBBIT5"– IOS ERROR ROUTINE USE INDICATOR
	. . . . . .1.		DCBIFLDT	"DCBBIT6"– POSSIBLE LOST DATA CONDITION SUCH AS FOR A PRINTER
45 (2D)	ADDRESS	3	DCBDEBA	– ADDRESS OF ASSOCIATED DEB
48 (30)	ADDRESS	4	DCBGET(0)	– ADDRESS OF GET MODULE
48 (30)	ADDRESS	4	DCBPUT(0)	– ADDRESS OF PUT MODULE
48 (30)	BITSTRING	1	DCBOFLG1	SAME AS DCBOFLGS BEFORE OPEN
49 (31)	ADDRESS	3	DCBGETA(0)	ADDRESS OF GET MODULE
49 (31)	ADDRESS	3	DCBPUTA	ADDRESS OF PUT MODULE
BISAM–QISAM INTERFACE
52 (34)	BITSTRING	1	DCBOPTCD	– OPTION CODES
	1. . . . . . .		DCBOPTW	"DCBBIT0"– WRITE VALIDITY CHECK (DASD) (BSAM, BPAM, QSAM, ISAM, BDAM)
	.1. . . . . .		DCBOPTUF	"DCBBIT1"– FULL–TRACK INDEX WRITE
	. .1. . . . .		DCBOPTM	"DCBBIT2"– MASTER INDEXES
	. . .1 . . . .		DCBOPTI	"DCBBIT3"– INDEPENDENT OVERFLOW AREA
	. . . . 1. . .		DCBOPTY	"DCBBIT4"– CYLINDER OVERFLOW AREA
	. . . . . .1.		DCBOPTL	"DCBBIT6"– DELETE OPTION
	. . . . . . .1		DCBOPTR	"DCBBIT7"– REORGANIZATION CRITERIA
53 (35)	BITSTRING	1	DCBMAC	– EXTENSION OF DCBMACRF FIELD FOR ISAM
	. . . . 1. . .		DCBMACUR	"DCBBIT4"– UPDATE FOR READ
	. . . . .1. .		DCBMACUW	"DCBBIT5"– UPDATE TYPE OF WRITE
	. . . . . .1.		DCBMACAW	"DCBBIT6"– ADD TYPE OF WRITE
	. . . . . . .1		DCBMACRE	"DCBBIT7"– READ EXCLUSIVE
54 (36)	SIGNED	1	DCBNTM	– NUMBER OF TRACKS THAT DETERMINE THE DEVELOPMENT OF A MASTER INDEX MAXIMUM PERMISSIBLE VALUE – 99
55 (37)	SIGNED	1	DCBCYLOF	– NUMBER OF TRACKS TO BE RESERVED ON EACH PRIME DATA CYLINDER FOR RECORDS THAT OVERFLOW FROM OTHER TRACKS ON THAT CYLINDER
56 (38)	ADDRESS	4	DCBSYNAD	– ADDRESS OF USER'S SYNAD ROUTINE
60 (3C)	SIGNED	2	DCBRKP	– RELATIVE POSITION OF FIRST BYTE OF KEY WITHIN EACH LOGICAL RECORD
62 (3E)	SIGNED	2	DCBBLKSI	– BLOCK SIZE
64 (40)	BITSTRING	8	DCBLPDT(0)	– FOR RESUME LOAD, THE LAST PRIME DATA TRACK ON THE LAST PRIME DATA CYLINDER IN THE FORM MBBCCHHR.
64 (40)	ADDRESS	4	DCBMSWA	– ADDRESS OF MAIN STORAGE WORK AREA FOR USE BY CONTROL PROGRAM WHEN NEW RECORDS ARE BEING ADDED TO AN EXISTING DATA SET
68 (44)	SIGNED	2	DCBSMSI	– NUMBER OF BYTES IN AREA RESERVED TO HOLD HIGHEST LEVEL INDEX
70 (46)	SIGNED	2	DCBSMSW	– NUMBER OF BYTES IN WORK AREA USED BY CONTROL PROGRAM WHEN NEW RECORDS ARE BEING ADDED TO DATA SET
72 (48)	ADDRESS	4	DCBMSHI(0)	– ADDRESS OF MAIN STORAGE AREA TO HOLD HIGHEST LEVEL INDEX
72 (48)	SIGNED	1	DCBNCP	– NUMBER OF COPIES OF READ–WRITE (TYPE K) CHANNEL PROGRAMS THAT ARE TO BE ESTABLISHED FOR THIS DCB. (99 MAXIMUM)
73 (49)	ADDRESS	3	DCBMSHIA	– SAME AS DCBMSHI ABOVE
76 (4C)	ADDRESS	4	DCBSETL	– ADDRESS OF SETL MODULE FOR QISAM. ADDRESS OF CHECK MODULE FOR BISAM
80 (50)	BITSTRING	1	DCBEXCD1	– FIRST BYTE IN WHICH EXCEPTIONAL CONDITIONS DETECTED IN PROCESSING DATA RECORDS ARE REPORTED TO THE USER
	1. . . . . . .		DCBEXNKY	"DCBBIT0"– LOWER KEY LIMIT NOT FOUND
	.1. . . . . .		DCBEXIDA	"DCBBIT1"– INVALID DEVICE ADDRESS FOR LOWER LIMIT
	. .1. . . . .		DCBEXNSP	"DCBBIT2"– SPACE NOT FOUND
	. . .1 . . . .		DCBEXINV	"DCBBIT3"– INVALID REQUEST
	. . . . 1. . .		DCBEXIER	"DCBBIT4"– UNCORRECTABLE INPUT ERROR
	. . . . .1. .		DCBEXOER	"DCBBIT5"– UNCORRECTABLE OUTPUT ERROR
	. . . . . .1.		DCBEXBLI	"DCBBIT6"– BLOCK COULD NOT BE REACHED (INPUT)
	. . . . . . .1		DCBEXBLU	"DCBBIT7"– BLOCK COULD NOT BE REACHED (UPDATE)
81 (51)	BITSTRING	1	DCBEXCD2	– SECOND BYTE IN WHICH EXCEPTIONAL CONDITIONS DETECTED IN PROCESSING DATA RECORDS ARE REPORTED TO THE USER
	1. . . . . . .		DCBEXSEQ	"DCBBIT0"– SEQUENCE CHECK
	.1. . . . . . .		DCBEXDUP	"DCBBIT1"– DUPLICATE RECORD
	. .1. . . . .		DCBEXCLD	"DCBBIT2"– DCB CLOSED WHEN ERROR WAS DETECTED
	. . .1 . . . .		DCBEXOFL	"DCBBIT3"– OVERFLOW RECORD
	. . . . 1. . .		DCBEXLTH	"DCBBIT4"– FOR PUT – LENGTH FIELD OF RECORD LARGER THAN LENGTH INDICATED IN DCBLRECL
	. . . . 1. . .		DCBEXRDE	"DCBBIT4"– READ EXCLUSIVE
82 (52)	SIGNED	2	DCBLRECL	– FOR FIXED–LENGTH RECORD FORMATS, LOGICAL RECORD LENGTH. FOR VARIABLE–LENGTH RECORD FORMATS, MAXIMUM LOGICAL RECORD LENGTH OR AN ACTUAL LOGICAL RECORD LENGTH CHANGED DYNAMICALLY BY USER WHEN CREATING THE DATA SET
84 (54)	ADDRESS	4	DCBESETL	– ADDRESS OF ESETL ROUTINE IN GET MODULE
88 (58)	ADDRESS	4	DCBLRAN	– ADDRESS OF READ–WRITE K MODULE OR EXCLUSIVE MODULE
92 (5C)	ADDRESS	4	DCBLWKN	– ADDRESS OF WRITE KN MODULE
96 (60)	ADDRESS	4	DCBRELSE	– WORK AREA FOR TEMPORARY STORAGE OF REGISTER CONTENTS
100 (64)	ADDRESS	4	DCBPUTX	– WORK AREA FOR TEMPORARY STORAGE OF REGISTER CONTENTS
104 (68)	ADDRESS	4	DCBRELEX	– ADDRESS OF READ EXCLUSIVE MODULE
108 (6C)	ADDRESS	4	DCBFREED	– ADDRESS OF DYNAMIC BUFFERING MODULE
112 (70)	SIGNED	1	DCBHIRTI	– NUMBER OF INDEX ENTRIES THAT FIT ON A PRIME DATA TRACK
113 (71)	CHARACTER	7	DCBFTMI2	– DIRECT ACCESS DEVICE ADDRESS OF FIRST TRACK OF SECOND LEVEL MASTER INDEX (IN THE FORM MBBCCHH)
120 (78)	CHARACTER	5	DCBLEMI2	– DIRECT ACCESS DEVICE ADDRESS OF LAST ACTIVE ENTRY IN SECOND LEVEL MASTER INDEX (IN THE FORM CCHHR)
125 (7D)	CHARACTER	7	DCBFTMI3	– DIRECT ACCESS DEVICE ADDRESS OF FIRST TRACK OF THIRD LEVEL MASTER INDEX (IN THE FORM MBBCCHH)
132 (84)	CHARACTER	5	DCBLEMI3	– DIRECT ACCESS DEVICE ADDRESS OF LAST ACTIVE ENTRY IN THIRD LEVEL MASTER INDEX (IN THE FORM CCHHR)
137 (89)	SIGNED	1	DCBNLEV	– NUMBER OF LEVELS OF INDEX
138 (8A)	CHARACTER	3	DCBFIRSH	– HHR OF FIRST DATA RECORD ON EACH CYLINDER. FOR VARIABLE LENGTH RECORD PROCESSING, R PORTION OF THIS FIELD IS ALWAYS X'01'.
141 (8D)	CHARACTER	1	DCBHMASK	– BYTE INDICATING 2301 OR NOT
	. . . . .111		DCBHMDRM	"X'07'"– DEVICE IS 2301 DRUM
	1111 1111		DCBHMNDM	"X'FF'"– DEVICE IS OTHER THAN 2301 DRUM
142 (8E)	CHARACTER	2	DCBLDT	– HH IS THE LAST PRIME DATA TRACK ON EACH CYLINDER
144 (90)	CHARACTER	1	DCBHIRCM	– HIGHEST POSSIBLE R FOR TRACKS OF THE CYLINDER AND MASTER INDICES
145 (91)	CHARACTER	1	DCBHIRPD	– HIGHEST R ON ANY PRIME TRACK IN DATA SET. FOR VARIABLE –LENGTH RECORDS, THIS REPRESENTS THE GREATEST NUMBER OF PHYSICAL RECORDS ON ANY PRIME TRACK IN THE DATA SET
146 (92)	CHARACTER	1	DCBHIROV	– FOR FIXED–LENGTH RECORD FORMAT, HIGHEST POSSIBLE R FOR OVERFLOW DATA TRACKS. FOR VARIABLE-LENGTH RECORD FORMAT, UNUSED.
147 (93)	CHARACTER	1	DCBHIRSH	– FOR FIXED–LENGTH RECORD FORMAT, R OF LAST DATA RECORD ON A SHARED TRACK, IF APPLICABLE. FOR VARIABLE–LENGTH RECORD FORMAT, UNUSED.
148 (94)	SIGNED	2	DCBTDC	– USER–SUPPLIED NUMBER OF RECORDS TAGGED FOR DELETION.
150 (96)	SIGNED	2	DCBNCRHI	– NUMBER OF STORAGE LOCATIONS NEEDED TO HOLD THE HIGHEST LEVEL INDEX
152 (98)	SIGNED	4	DCBRORG3	– FOR EACH USE OF DATA SET, NUMBER OF READ OR WRITE ACCESSES TO AN OVER FLOW RECORD WHICH IS NOT FIRST IN A CHAIN OF SUCH RECORDS
156 (9C)	SIGNED	4	DCBNREC	– NUMBER OF LOGICAL RECORDS IN PRIME DATA AREA
160 (A0)	BITSTRING	1	DCBST	– STATUS INDICATORS
	1. . . . . . .		DCBSTSSM	"DCBBIT0"– SINGLE SCHEDULE MODE
	.1. . . . . .		DCBSTKSQ	"DCBBIT1"– KEY SEQUENCE CHECKING IS TO BE PERFORMED
	. .1. . . . .		DCBSTLOD	"DCBBIT2"– LOADING HAS COMPLETED. SET TO 1 BY CLOSE ROUTINE AND TO 0 BY FIRST EXECUTION OF PUT ROUTINE.
	. . .1 . . . .		DCBSTNCY	"DCBBIT3"– EXTENSION OF DATA SET WILL BEGIN ON NEW CYLINDER
	. . . . .1. .		DCBSTNMC	"DCBBIT5"– FIRST MACRO INSTRUCTION NOT YET RECEIVED
	. . . . . .1.		DCBSTLBF	"DCBBIT6"– LAST BLOCK FULL
	. . . . . . .1		DCBSTLTF	"DCBBIT7"– LAST TRACK FULL
161 (A1)	CHARACTER	7	DCBFTCI	– DIRECT ACCESS DEVICE ADDRESS OF FIRST TRACK OF CYLINDER INDEX (IN THE FORM MBBCCHH).
168 (A8)	CHARACTER	1	DCBHIIOV	– FOR FIXED LENGTH RECORD FORMAT, HIGHEST POSSIBLE R FOR INDEPENDENT OVERFLOW DATA TRACKS. FOR VARIABLE LENGTH RECORD FORMAT, UNUSED
169 (A9)	CHARACTER	7	DCBFTMI1	– DIRECT ACCESS DEVICE ADDRESS OF FIRST TRACK OF FIRST LEVEL MASTER INDEX (IN THE FORM MBBCCHH).
176 (B0)	SIGNED	1	DCBNTHI	– NUMBER OF TRACKS OF HIGH–LEVEL INDEX
177 (B1)	CHARACTER	7	DCBFTHI	– DIRECT ACCESS DEVICE ADDRESS OF FIRST TRACK OF HIGHEST LEVEL INDEX (IN THE FORM MBBCCHH).
184 (B8)	CHARACTER	8	DCBLPDA	– DIRECT ACCESS DEVICE ADDRESS OF LAST PRIME DATA RECORD IN PRIME DATA AREA (IN THE FORM MBBCCHHR).
192 (C0)	CHARACTER	5	DCBLETI	– DIRECT ACCESS DEVICE ADDRESS OF LAST ACTIVE NORMAL ENTRY OF TRACK INDEX ON LAST ACTIVE CYLINDER (IN THE FORM CCHHR).
197 (C5)	CHARACTER	1	DCBOVDEV	– DEVICE TYPE FOR INDEPENDENT OVERFLOW
THESE SAME MASKS APPLY TO DCBDEVT FOR ISAM DIRECT ACCESS
	. . . . . .1.		DCBDVI01	"X'02'"– 2301 PARALLEL DRUM
	. . . . . .11		DCBDVI03	"X'03'"– 2303 SERIAL DRUM
	. . . . .1. .		DCBDVI02	"X'04'"– 2302 DISK STORAGE
	. . . . .1.1		DCBDVI05	"X'05'"– 2305 DRUM
	. . . . 1. . .		DCBDVI14	"X'08'"– 2314 DISK STORAGE FACILITY
	. . . . 1. .1		DCBDVI30	"X'09'"– 3330 DISK STORAGE FACILITY
198 (C6)	SIGNED	2	DCBNBOV	– FOR FIXED LENGTH RECORD FORMAT, RESERVED. FOR VARIABLE LENGTH RECORD FORMAT, IF THE INDEPENDENT OVERFLOW OPTION IS SELECTED, CONTAINS, IN BINARY, NUMBER OF BYTES LEFT ON CURRENT TRACK OF INDEPENDENT OVERFLOW AREA
200 (C8)	CHARACTER	5	DCBLECI	– DIRECT ACCESS DEVICE ADDRESS OF LAST ACTIVE ENTRY IN CYLINDER INDEX (IN THE FORM CCHHR).
205 (CD)	BITSTRING	1		– RESERVED
206 (CE)	SIGNED	2	DCBRORG2	– NUMBER OF TRACKS (PARTIALLY OR WHOLLY) REMAINING IN INDEPENDENT OVERFLOW AREA
208 (D0)	CHARACTER	5	DCBLEMI1	– DIRECT ACCESS DEVICE ADDRESS OF LAST ACTIVE ENTRY IN FIRST LEVEL MASTER INDEX (IN THE FORM CCHHR).
213 (D5)	BITSTRING	1		– RESERVED
214 (D6)	SIGNED	2	DCBNOREC	– NUMBER OF LOGICAL RECORDS IN AN OVERFLOW AREA
216 (D8)	CHARACTER	8	DCBLIOV	– DIRECT ACCESS DEVICE ADDRESS OF LAST AREA (IN THE FORM MBBCCHHR).
224 (E0)	SIGNED	2	DCBRORG1	– NUMBER OF CYLINDER OVERFLOW AREAS THAT ARE FULL
226 (E2)	BITSTRING	2		– RESERVED
228 (E4)	ADDRESS	4	DCBWKPT1	– POINTER TO WORK AREA OR TO CONSTRUCTED CHANNEL PROGRAM FOR WHICH SPACE IS OBTAINED BY GETMAIN MACRO INSTRUCTIONS ISSUED BY OPEN EXECUTORS
232 (E8)	ADDRESS	4	DCBWKPT2	– ADDITIONAL POINTER AS IN DCBWKPT1
236 (EC)	ADDRESS	4	DCBWKPT3	– ADDITIONAL POINTER AS IN DCBWKPT1
240 (F0)	ADDRESS	4	DCBWKPT4	– ADDITIONAL POINTER AS IN DCBWKPT1
244 (F4)	ADDRESS	4	DCBWKPT5	– ADDITIONAL POINTER AS IN DCBWKPT1
248 (F8)	ADDRESS	4	DCBWKPT6	– ADDITIONAL POINTER AS IN DCBWKPT1