Data set creation attributes syntax

The data set creation attributes are used to define the structure of MVS data sets when creating a file. These attributes correspond to the data control block (DCB) or the job control language (JCL) parameters used to define an MVS data set when it is created. See z/OS MVS JCL Reference for more information about data set creation attributes.

The data set creation attributes do not apply for z/OS UNIX files.

Table 1 describes data set creation attributes. Defaults are underlined in this format. You can override these attributes by using the mount command or file creation command. For PDS and PDSE, members have the same attributes as the data set attributes, so the file creation attributes specified for members are ignored.

Table 1. Data set creation attributes
Data Set Creation Attribute	Description
blks Specifies that disk space is allocated by blocks, except for VSAM data sets. See the space attribute in this table. cyls Specifies that disk space is allocated by cylinders. recs Specifies that disk space is allocated by records for VSAM data sets. The blks and recs attribute values are identical for VSAM data sets. trks Specifies that the disk space is allocated by tracks.
blksize(0 \| quan) Specifies the maximum length, in bytes, of a physical block on disk. The value of quan can range from 0 (the default value) to 32,760. If blksize(0) is specified, the system determines an optimal block size to use. System determined block size is not supported by the system for Direct Access (DA) data sets. z/OS NFS Server uses the following formula to calculate the block size for a DA data set depending on the record format: `F \| FB blksize = lrecl V \| VB blksize = lrecl + 4 VS \| VBS blksize = 6160`
dataclas(class_name) Specifies the data class associated with the file creation. The class_name must be defined to DFSMS before it can be used by the client. The system-managed storage automatic class selection (ACS) routine must also assign a storage class to the file being created. If a data class is not specified in the attribute file, dataclas() is displayed by the showattr client enabling command. For more information about data classes, see z/OS DFSMSdfp Storage Administration.
dir(27 \| quan) Specifies the number of 256-byte records needed in the directory of a PDS. Use the dir attribute with the mkdir command when you create a PDS. The value of quan can range from 1 to 16,777,215. The default value is 27. The maximum number of PDS members is 14,562.
dsntype(library \| pds) Specifies whether a PDSE or a PDS is to be created when the mkdir client command is used. The following options can be specified. library Specifies partitioned data set extended (PDSE) pds Specifies partitioned data set (PDS) You cannot create a PDS (or PDSE) within another PDS (or PDSE). For more information about creating a PDS or a PDSE, see z/OS DFSMS Using Data Sets.
dsorg(org) Specifies the organization of a data set. The following org values can be specified. da Direct data set indexed VSAM KSDS data set nonindexed VSAM ESDS data set numbered VSAM RRDS data set ps Physical sequential (ps) data set The dsorg attribute is ignored for directory-oriented client commands. If you are using VSAM data sets in binary mode, then nonindexed is recommended.
keys(len, off) Specifies the length and offset of the keys for VSAM KSDS data sets. The keys attribute can only be specified when using dsorg(indexed). The len and off values are specified in bytes. len Specifies a value between 1 and 255. The default value is 64. off Specifies a value between 0 and 32,760. The default value is 0. When you create a VSAM KSDS data set, the records you are loading into it must be keyed-sequenced or the write fails. Each write of the data set is treated like a first load, and requires that the records being loaded are in ascending key sequence.
lrecl(8196 \| quan) The value of quan specifies a record length. Length, in bytes, for fixed-length records. Maximum length, in bytes, for variable-length records. If the blksize attribute is specified, the value must be at least 4 bytes less than the blksize quantity. The value of quan can range from 1 to 32,760. The default value is 8196.
mgmtclas(mgmt_class_name) Specifies the management class associated with the file creation. The mgmt_class_name must be defined to DFSMS/MVS before it can be used by the client. The system-managed storage automatic class selection (ACS) routine must also assign a storage class to the file being created. If a management class is not specified in the attribute file, mgmtclas() is displayed by the showattr client enabling command. For more information about management classes, see z/OS DFSMSdfp Storage Administration.
recfm(cccc) Specifies the format and characteristics of the records in the data set. The value of cccc can be 1 to 4 characters, in one of the following combinations. `[f \| fb \| fs \| fbs] [a\|m] u [a\|m] [v \| vb \| vs \| vbs] [a\|m]` The following are valid record format characters. `a` ANSI control codes `b` Blocked `f` Fixed-length records `m` Machine control codes `s` Spanned for variable records, standard format for fixed records `u` Undefined-length records `v` Variable-length records The recfm format characters `v`, `f` and `u` are mutually exclusive. The recfm format characters `a` and `m` are mutually exclusive.The format character `s` is not allowed for a PDS or PDSE.
recordsize(avg,max) Specifies the average and maximum record size for VSAM data sets. The avg and max values are specified in bytes. They can each range from 1 to 32,760. The default values are 512 and 4K, respectively. These values must be equal for VSAM RRDS.
rlse Specifies that unused space should be released from the data set the first time a new data set is closed. For slow clients with long pauses between writes, the rlse attribute causes space to be released from the primary extent prematurely. Any additional writes will cause secondary space to be allocated. norlse Specifies that unused space should not be released from the data set.
shareoptions(xreg,xsys) Specifies the cross-region and cross-system share options for a VSAM data set. The value of xreg ranges from `1` to `4`. The value of xsys is either `3` or `4`. The default values are `1` and `3`, respectively. For more information, see "Sharing VSAM Data Sets" in z/OS DFSMS Using Data Sets
This applies to VSAM data sets only. For spanned records of non-VSAM data sets, see the entry for the recfm attribute in this table. spanned Specifies that VSAM KSDS or ESDS data sets can contain records that span control intervals (spanned records). nonspanned Specifies that data sets do not have spanned records.
space(prim[,aux]) Specifies the amount of primary and auxiliary space allocated for a new data set on a direct access volume. The value of prim is the number (from 0 to 16,777,215) of primary tracks, cylinders, or data blocks in the data set. The value of aux (optional) is the number (from 0 to 16,777,215) of additional tracks, cylinders, or blocks allocated if more space is needed. If the space attribute is not specified, the default is used. The default values are 100 and 10, respectively.
storclas(class_name) Specifies the storage class associated with the file creation. The class_name must be defined to the DFSMS efore it can be used by the client. If a storage class is not specified in the attribute file, storclas() is displayed by the showattr client enabling command. For more information about storage classes, see z/OS DFSMSdfp Storage Administration.
unit(unit_name) Specifies the unit on which to create a data set. The unit_name is a generic or symbolic name of a group of DASD devices. The unit_name must be specified as 3390 for extended format data sets. If a side file name is not specified in the attribute file, unit() is displayed by the showattr client enabling command. Note: You cannot create or access tape data sets on an z/OS host using the z/OS NFS server. You cannot create extended format data sets with the z/OS NFS server, except using ACS routines.
vol(volser) or volume(volser) Specifies the name of the DASD volume to use to store the created data set. volume or vol is the keyword, and the value of volser represents the volume name. If a volume is not specified in the attribute file, volume() is displayed by the showattr client enabling command. If a data set is system-managed, as determined by the DFSMS automatic class selection (ACS) routines, you can omit this attribute.