ABCs of z/OS System Programming Volume 3 - IBM Redbooks

► The AVGREC attribute indicates the scale factor for the primary and secondary allocation
values. In the example, an AVGREC value of M indicates that the primary and secondary
values of 5 are each to be multiplied by 1 048 576.
► For system-managed data sets, the device-dependent volume serial number and unit
information is no longer required, because the volume is assigned within a storage group
selected by the ACS routines.
Overriding data class attributes with JCL
In a DFSMS environment, the JCL to allocate a data set is simpler and has no
device-dependent keywords.
Table 5-2 lists the attributes a user can override with JCL.
Table 5-2 Data class attributes that can be overridden by JCL
JCL DD statement keyword Use for
RECORG,KEYLEN,KEYOFF Only VSAM
RECFM Sequential (PO or PS)
LRECL,SPACE,AVGREC, RETPD or EXPDT,
VOLUME (volume count)
For more information about data classes refer to 5.8, “Using data classes” on page 251 and
5.32, “Data class attributes” on page 294.
As previously mentioned, in order to use a data class, the data set does not have to be
system-managed. An installation can take advantages of a minimal SMS configuration to
simplify JCL use and manage data set allocation.
For information about managing data allocation, see z/OS DFSMS: Using Data Sets,
SC26-7410.
298 ABCs of z/OS System Programming Volume 3
All data set types
DSNTYPE PDS or PDSE