DCB subparameters

DCB subparameters	Access method							Description of subparameters
DCB subparameters	B D A M	B P A M	B S A M	B T A M	E X C P	G A M	Q S A M	Description of subparameters
BFALN	X	X	X		X		X	BFALN={F\|D} Specifies that each buffer starts either on a word boundary that is not also a doubleword boundary or on a doubleword boundary. If both BFALN and BFTEK are specified, they must be specified from the same source. Default: D (doubleword) Note: Do not code the BFALN subparameter with DCB subparameter GNCP, or with DD parameters DDNAME or QNAME.
BFTEK	X		X	X			X	BDAM and BSAM: BFTEK=R R Specifies that the data set is being created for or contains variable-length spanned records. Do not specify R for a PDSE. BTAM: BFTEK=D D Specifies that dynamic buffering is to be used in the processing program; if dynamic buffering is specified, a buffer pool also must be defined. QSAM: BFTEK={S\|A} S Specifies simple buffering (default). Simple buffering may be coded at any time for QSAM files. A Specifies locate mode logical record interface for spanned records. QSAM obtains a logical record area and assembles the physical record segments of a spanned record into that logical record area. This forms a complete logical record before pointing the user to it. This parameter value may be specified only for RECFM=VS or RECFM=VBS files; if specified without RECFM=VS\|VBS, the specification is ignored. Locate mode must be used together with this parameter value. Note: If you use locate mode on a RECFM=VS\|VBS file and BFTEK=A is not specified, the results may include processing the segments of a spanned record as separate records, issuance of system completion (abend) code X'002' with reason code X'04', or other unpredictable results. If you specify BFTEK=A with move mode, a system completion (abend) code X'013' with reason code X'5C' is issued. For information about the locate and move modes in the DCB subparameters BFTEK and VBS, see z/OS DFSMS Macro Instructions for Data Sets. If you specify both BFALN and BFTEK, you must specify them from the same source. Note: Do not code the BFTEK subparameter with DCB subparameter GNCP, or with DD parameters DDNAME or QNAME. Note: For compatibility purposes with previous operating systems, the system accepts BFTEK=E.
BLKSIZE	X	X	X		X		X	BLKSIZE={value\|valueK\|valueM\|valueG} Specifies the maximum length, in bytes, of a block. value Specifies the maximum length of a block. The number you specify for BLKSIZE depends on the device type and the record format for the data set. The maximum is 32,760 for DASD data sets and 2,147,483,648 for tape, except for data sets on magnetic tape with ISO/ANSI/FIPS labels, where the minimum value for BLKSIZE is 18 bytes and the maximum is 2048 bytes. (To allow a value greater than 2048, use installation exit routine IFG0193G, described in z/OS DFSMS Installation Exits.) valueK Specifies the maximum length, in kilobytes, of a block. (1 kilobyte = 1024 bytes.) The maximum is 2097152. If 2097152K is coded, the block size assigned will be the maximum: 2,147,483,648. valueM Specifies the maximum length, in megabytes, of a block. (1 megabyte = 1024 kilobytes.) The maximum is 2048. If 2048M is coded, the block size assigned will be the maximum: 2,147,483,648. valueG Specifies the maximum length, in gigabytes, of a block. (1 gigabyte = 1024 megabytes.) The maximum is 2G. If 2G is coded, the block size assigned will be the maximum: 2,147,483,648. If you code the BLKSIZE subparameter in the DCB macro instruction or on a DD statement that defines an existing data set with standard labels, the DCB BLKSIZE overrides the block size specified in the label. BLKSIZE can be coded but will have no effect on EXCP processing. The number you specify for BLKSIZE directly affects the amount of space obtained for data sets allocated in records, and for data sets allocated in blocks where the block length (blklgth) is zero. Default: If you do not code BLKSIZE, the system can, under certain conditions, determine an optimum block size for the data. For detailed information about system-determined block size, see z/OS DFSMS Using Data Sets. Note: Do not code the BLKSIZE subparameter with the BUFSIZE subparameter.
BUFIN								BUFIN=buffers Specifies the number of buffers to be assigned initially for receiving operations for each line in the line group. The combined BUFIN and BUFOUT values must not be greater than the number of buffers in the buffer pool for this line group (not including those for disk activity only). Default: 1 Note: Do not code the BUFIN subparameter with DCB subparameter BUFNO, or DD parameters DDNAME, QNAME.
BUFL	X	X	X		X		X	BUFL=bytes Specifies the length, in bytes, of each buffer in the buffer pool. The maximum is 32,760. Note: Do not code the BUFL subparameter with DD parameter DDNAME.
BUFMAX								BUFMAX=buffers Specifies the maximum number of buffers to be allocated to a line at one time. Number must be 2 through 15 and must be equal to or greater than the larger of the numbers specified by the BUFIN and BUFOUT subparameters. Default: 2 Note: Do not code the BUFMAX subparameter with DCB subparameter NCP, or DD parameters DDNAME, QNAME.
BUFNO	X	X	X	X	X		X	BUFNO=buffers Specifies the number of buffers to be assigned to the DCB. The maximum normally is 255, but can be less because of the size of the region. Note: Do not code the BUFNO subparameter with DCB subparameters BUFIN, BUFOUT, or DD parameter QNAME.
BUFOFF			X				X	BUFOFF={n\|L} n Specifies the length, in bytes, of the block prefix used with an ASCII tape data set. For input, n can be 0 through 99. For output, n must be 0 for writing an output data set with fixed-length or undefined-length records. L Specifies that the block prefix is 4 bytes and contains the block length. BUFOFF=L is valid only with RECFM=D. For output, only BUFOFF=L is valid. Note: Do not code the BUFOFF subparameter with DD parameters DDNAME, QNAME.
BUFOUT								BUFOUT=buffers Specifies the number of buffers to be assigned initially for sending operations for each line in the line group. The combined number of BUFIN and BUFOUT values must not be greater than the number of buffers in the buffer pool for this line group (not including those for disk activity only) and cannot exceed 15. Default: 2 Note: Do not code the BUFOUT subparameter with DCB subparameter BUFNO, or DD parameter DDNAME.
BUFSIZE								BUFSIZE=bytes Specifies the length, in bytes, of each of the buffers to be used for all lines in a particular line group. Length must be 31 through 65535 bytes. Note: Do not code the BUFSIZE subparameter with DCB subparameter BLKSIZE, or DD parameters DDNAME, QNAME.
CPRI								XCPRI={R\|E\|S} Specifies the relative transmission priority assigned to the lines in this line group. R Specifies that processor receiving has priority over processor sending. E Specifies that receiving and sending have equal priority. S Specifies that processor sending has priority over processor receiving. Note: Do not code the CPRI subparameter with DCB subparameter THRESH, or DD parameters DDNAME, OUTLIM, QNAME.
CYLOFL								CYLOFL=tracks Specifies the number of tracks on each cylinder to hold the records that overflow from other tracks on that cylinder. The maximum is 99. Specify CYLOFL only when OPTCD=Y. Note: Do not code the CYLOFL subparameter with DCB subparameter RESERVE, or DD parameters DDNAME, FCB, QNAME, UCS.
DEN			X		X		X	DEN={1\|2\|3\|4} Specifies the magnetic density, in number of bits-per-inch, used to write a magnetic tape data set. `DEN 7-track tape 9-track tape 1 556 - 2 800 800 (NRZI) 3 - 1600 (PE) 4 - 6250 (GCR)` NRZI Non-return-to-zero inverted recording mode. PE Phase encoded recording mode. GCR Group coded recording mode. Default: 800 bpi assumed for 7-track tape and 9-track without dual density. 1600 bpi assumed for 9-track with dual density or phase-encoded drives. 6250 bpi assumed for 9-track with 6250/1600 bpi dual density or group coded recording tape. Note: Do not code the DEN subparameter with DD parameters DDNAME, QNAME.
DIAGNS	X	X	X	X	X	X	X	DIAGNS=TRACE Specifies the OPEN/CLOSE/EOV trace option, which gives a module-by-module trace of OPEN/CLOSE/EOV’s work area and the DCB. If the generalized trace facility (GTF) is not running and tracing user events, DIAGNS is ignored. See z/OS DFSMSdfp Diagnosis for more information.
DSORG	X	X	X	X	X	X	X	XDSORG=organization Specifies the organization of the data set and indicates whether the data set contains any location-dependent information that would make the data set unmovable. Note: Do not code the DSORG subparameter with DD parameters DDNAME, QNAME, RECORG. Organization \| Access Method ___________________________________ _ _____________________ PS Physical sequential data set \| BSAM,EXCP,QSAM, PSU Physical sequential data set \| BSAM,QSAM,EXCP that contains \| location-dependent information \| DA Direct access data set \| BDAM,EXCP DAU Direct access data set that \| BDAM,EXCP contains location-dependent \| information \| PO Partitioned data set \|BPAM,EXCP (PDS or PDSE) \| POU Partitioned data set (PDS) that\| BPAM,EXCP contains location-dependent \| information \| CX Communications line group \| BTAM GS Graphic data control block \| GAM
EROPT				X			X	EROPT=x BTAM: Requests the BTAM on-line terminal test option. x=T QSAM: Specifies the option to be executed if an error occurs in reading or writing a record. x=ACC System is to accept the block causing the error. x=SKP System is to skip the block causing the error. x=ABE System is to cause abnormal end of task. Default ABE Note: Do not code the EROPT subparameter with DD parameters DDNAME, QNAME.
FUNC			X				X	FUNC={I\|R\|P\|W\|D\|X\|T} Specifies the type of data set to be opened for a 3505 Card Reader or 3525 Card Punch. Unpredictable results will occur if coded for other than a 3505 or 3525. I Data set is for punching and printing cards. R Data set is for reading cards. P Data set is for punching cards. W Data set is for printing. D Protected data set is for punching. X Data set is for both punching and printing. T Two-line print option. The only valid combinations of these values are: `I WT RWT RPWXT PWX R RP PW RPWD RPWX P RPD PWXT RWX RWX W RW RPW RWXT` Default: P, for output data set. R, for input data set. Note: Do not code the FUNC subparameter with the data-set-sequence number of the DD LABEL parameter, or DD parameters DDNAME, QNAME.
GNCP						X		GNCP=n Specifies the maximum number of I/O macro instructions that the program will issue before a WAIT macro instruction. Note: Do not code the GNCP subparameter with DCB subparameters BFALN, BFTEK, or DD parameters DDNAME, QNAME.
INTVL								INTVL={n\|0} Specifies the interval, in seconds, between passes through an invitation list. Default: 0 Note: Do not code the INTVL subparameter with DD parameters DDNAME, FCB, QNAME, UCS.
IPLTXID								IPLTXID=member Specifies the name of the partitioned data set (PDS) member that you want loaded into a 3704/3705 Communications Controller. The DCB IPLTXID subparameter overrides IPLTXID in the TERMINAL macro representing the NCP. Note: Do not code the IPLTXID subparameter with DD parameters DDNAME, DSNAME, QNAME.
KEYLEN	X	X	X		X			KEYLEN=bytes The KEYLEN keyword subparameter is described on the DD KEYLEN parameter, section KEYLEN parameter.
LIMCT	X							LIMCT={blocks\|tracks} Specifies how many blocks (if relative block addressing is used) or how many tracks (if relative track addressing is used) are to be searched for a free block or available space. This kind of search occurs only when DCB OPTCD=E is also specified; otherwise, LIMCT is ignored. If the LIMCT number equals or exceeds the number of blocks or tracks in the data set, the entire data set is searched. Note: Do not code the LIMCT subparameter with DD parameters DDNAME, QNAME.
LRECL		X	X		X		X	LRECL=bytes The LRECL keyword subparameter is described on the DD LRECL parameter, section LRECL parameter.
MODE			X		X		X	`MODE= {C [O]} {E [R]}` Specifies the mode of operation to be used with a card reader, a card punch, or a card read-punch. C Card image (column binary) mode E EBCDIC mode O Optional mark read mode R Read column eliminate mode If you specify R, you must also specify either C or E. Do not code the MODE subparameter for data entered through the input stream except in a JES3 system. Do not code MODE=C for JES2 or JES3 output. Default: E Note: Do not code the MODE subparameter with DCB subparameters KEYLEN, PRTSP, TRTCH, or DD parameters DDNAME, KEYLEN, QNAME.
NCP		X	X					NCP=n Specifies the maximum number of READ or WRITE macro instructions that may be issued before a CHECK macro instruction is issued to test for completion of the I/O operation. The maximum number is 255 for BSAM and BPAM, but may actually be smaller depending on the size of the address space. If chained scheduling is used, the number should be greater than 1. Default: 1 Note: Do not code the NCP subparameter with DCB subparameter BUFMAX, or DD parameters DDNAME, QNAME.
NTM								NTM=tracks Specifies the number of tracks to be used for a cylinder index. When the specified number of tracks has been filled, a master index is created. The DCB NTM is needed only when the DCB OPTCB=M. If you specify OPTCD=M but omit NTM, the master index option is ignored. Note: Do not code the NTM subparameter with DCB subparameter PCI, or DD parameters DDNAME, QNAME.
OPTCD	X	X	X		X		X	Specifies the optional services to be performed by the control program. All optional services must be requested in one source, that is, in the data set label of an existing data set, in the DCB macro, or in the DD DCB parameter. However, the processing program can modify the DCB OPTCD field. Code the characters in any order; when coding more than one, do not code commas between the characters. Note: Do not code the OPTCD subparameter with DD parameter DDNAME. `BDAM: OPTCD= {A}[E][F][W] {R}` A indicates that the actual device addresses are to be specified in READ and WRITE macro instructions. R indicates that relative block addresses are to be specified in READ and WRITE macro instructions. E indicates that an extended search (more than one track) is to be performed for a block of available space. LIMCT must also be coded. Do not code LIMCT=0 because it will cause an abnormal termination when a READ or WRITE macro instruction is executed. F indicates that feedback can be requested in READ and WRITE macro instructions and the device is to be identified in the same form as it was presented to the control program. W requests a validity check for write operations on direct access devices.
OPTCD (continued)								BPAM: OPTCD= {C\|W\|CW} C has no effect. W requests a validity check for write operations. `BSAM and QSAM: OPTCD= {B } {T } {U[C] } {C[T][B][U] } {H[Z][B] } {J[C][U] } {W[C][T][B][U]} {Z[C][T][B][U]} {Q[C][T][B] } {Z }` B requests that the end-of-volume (EOV) routine disregard the end-of-file (EOF) recognition for magnetic tape. For an input data set on a standard-labeled (SL or AL) tape, the EOV routine treats EOF labels as EOV labels until the volume serial list is exhausted. This option allows SL or AL tapes to be read out of volume sequence or to be concatenated to another tape with the same data set name using one DD statement. See "Data Sets that Span Libraries" in z/OS MVS JCL User's Guide for a description of allocation processing for multi-volume data sets created in different tape libraries. C requests chained scheduling. H requests hopper empty exit for optical readers or bypass of DOS checkpoint records. J for a data set to be printed on an AFP printer, instructs the system that the logical record for each output data line contains a table reference character (TRC). The TRC identifies which character arrangement table in the CHARS parameter is to be used to print the line. Before specifying OPTCD=J, see PSF for z/OS: User's Guide.
OPTCD (continued)								BSAM and QSAM (continued): Q indicates that all the user data in the data set is in ASCII. BSAM or QSAM converts the records from ASCII to EBCDIC when reading and converts the records from EBCDIC to ASCII when writing. The data set must reside on magnetic tape and must not contain IBM® standard labels. The record format (RECFM) must not be V but can be D. If the label type is ISO/ANSI/FIPS, specified as LABEL=(,AL), the system forces OPTCD=Q. T requests user totaling facility. T cannot be specified for a SYSIN or sysout data set. U for 1403 or 3211 Printers with the Universal Character Set (UCS) feature and for the 3800, permits data checks and allows analysis by an appropriate error analysis routine. If U is omitted, data checks are not recognized as errors. W requests a validity check for write operations on direct access devices. Requests "tape write immediate" mode on a cartridge tape device such as the IBM 3490 Magnetic Tape Subsystem. Z for magnetic tape reel input, requests that the control program shorten its normal error recovery procedure. When specified, a data check is considered permanent after five unsuccessful attempts to read a record. OPTCD=Z is ignored if chained scheduling or a tape cartridge is used. For a PDSE, all options except OPTCD=J are ignored. EXCP: OPTCD=Z Z for magnetic tape reel input, requests that the control program shorten its normal error recovery procedure. When specified, a data check is considered permanent after five unsuccessful attempts to read a record. OPTCD=Z has no effect on a tape cartridge.
PCI								`{([N][,N])} PCI= {([R][,R])} {([A][,A])} {([X][,X])}` Specifies (1) whether or not a program-controlled interruption (PCI) is to be used to control the allocation and freeing of buffers and (2) how these operations are to be performed. The first operand applies to receiving operations and the second to sending operations. N specifies that no PCIs are taken while filling buffers during receiving operations or emptying buffers during sending operations. R specifies that after the first buffer is filled or emptied, a PCI occurs during the filling or emptying of each succeeding buffer. The completed buffer is freed, but no new buffer is allocated to take its place. A specifies that after the first buffer is filled or emptied, a PCI occurs during the filling or emptying of the next buffer. The first buffer is freed, and a buffer is allocated to take its place. X specifies that after a buffer is filled or emptied, a PCI occurs during the filling or emptying of the next buffer. The first buffer is not freed, but a new buffer is allocated. You can omit the parentheses if you code only the first operand. Default: (A,A) Note: Do not code the PCI subparameter with DCB subparameter NTM, or DD parameters DDNAME, QNAME.
PRTSP			X		X		X	PRTSP={0\|1\|2\|3} Specifies the line spacing for an online printer. PRTSP is valid only for an online printer and only if the RECFM is not A or M. PRTSP=2 is ignored if specified with the DD SYSOUT parameter. 0 - spacing is suppressed, 1 - single, 2 - double, 3 - triple spacing JES2 ignores PRTSP for sysout data sets. Default: 1 Note: Do not code the PRTSP subparameter with DCB subparameters KEYLEN, MODE, STACK, TRTCH, or DD parameters DDNAME, KEYLEN, QNAME.
RECFM	X	X	X		X		X	RECFM=format The RECFM keyword subparameter is described on the DD RECFM parameter, section RECFM parameter.
RESERVE								RESERVE=(bytes1,bytes2) Specifies the number of bytes (0 through 255) to be reserved in a buffer for insertion of data by the DATETIME and SEQUENCE macros. bytes1 indicates the number of bytes to be reserved in the first buffer that receives an incoming message. bytes2 indicates the number of bytes to be reserved in all the buffers following the first buffer in a multiple-buffer header situation. Default: (0,0) Note: Do not code the RESERVE subparameter with DCB subparameters CYLOFL, RKP, or DD parameters DDNAME, KEYOFF, QNAME, UCS.
RKP					X			RKP=number With SMS, use the DD KEYOFF or DATACLAS parameter. Specifies the position of the first byte of the record key in each logical record. The first byte of a logical record is position 0. If RKP=0 is specified for blocked fixed-length records, the key begins in the first byte of each record. OPTCD=L must not be specified. If RKP=0 is specified for unblocked fixed-length records, the key is not written in the data field. OPTCD=L can be specified. For variable-length records, the relative key position must be 4 or greater, if OPTCD=L is not specified; the relative key position must be 5 or greater, if OPTCD=L is specified. For EXCP processing, RKP can be coded but is ignored. Default: 0 Note: Do not code the RKP subparameter with DCB subparameter RESERVE, or DD parameters DDNAME, FCB, KEYOFF, UCS.
STACK			X		X		X	STACK={1\|2} Specifies which stacker bin is to receive a card. Default: 1 Note: Do not code the STACK subparameter with DCB subparameters KEYLEN, PRTSP, TRTCH, or DD parameters DDNAME, KEYLEN, QNAME.
THRESH								THRESH=nn Specifies the percentage of the nonreusable disk message queue records that are to be used before a flush closedown occurs. Default: Closedown occurs when 95 percent of the records have been used. Note: Do not code the THRESH subparameter with DCB subparameter CPRI, or DD parameters DDNAME, OUTLIM, QNAME.
TRTCH			X		X		X	TRTCH={C\|E\|ET\|T}\|{COMP\|NOCOMP} With C, E, T, or ET: specifies the recording technique for 7-track tape. C specifies data conversion, odd parity, and no translation. E specifies no data conversion, even parity, and no translation. T specifies no data conversion, odd parity, and that BCD to EBCDIC translation is required when reading and EBCDIC to BCD translation when writing. ET specifies no data conversion, even parity, and that BCD to EBCDIC translation is required when reading and EBCDIC to BCD translation when writing. Default: no conversion, odd parity, and no translation. With COMP or NOCOMP: specifies data compaction or no data compaction on a tape device enabled for compaction. Data compaction is not supported with ISO/ANSI labels. COMP specifies data compaction. NOCOMP specifies no data compaction Defaults: On an IBM standard label tape, data sets after the first data set have the same compaction value (COMP or NOCOMP) as the first data set. The system ignores any compaction specified on data sets after the first. The system takes the compaction value from the first source that specifies it. The following sources can specify compaction: TRTCH subparameter. Data class, as set by the storage administrator. The tape, however, does not have to be system-managed. DEVSUPxx member of SYS1.PARMLIB. The hardware model. For the IBM 3480, the default is NOCOMP. For the IBM 3490, the default is COMP. See z/OS MVS JCL User's Guide for information about using IEFBR14 and the TRTCH subparameter. Note: Do not code the TRTCH subparameter with DCB subparameters KEYLEN, MODE, PRTSP, STACK, or DD parameters DDNAME, KEYLEN, QNAME. Note: TRTCH is not applicable for DASD data sets. If specified, it will be ignored.