Defining VSAM attributes and specifying media types for data class

From Page 2 of the Data Class Define panel, use the DOWN command to view Page 3, on which you specify VSAM attributes and media.

Recorg

Specifies the data set organization, and it resembles the RECORG DD attribute. If you specify a Recorg value, you cannot specify the Recfm attribute. A blank value specifies either a physical sequential or a partitioned organization (non-VSAM data set).

If you do not specify a Recorg value for data sets with a data class, assigned either by JCL or ACS routine, the DSORG defaults to either physical sequential (PS) or partitioned organization (PO). Data class does not have a DSORG field. To specify a physical sequential data set, specify RECFM. To specify partitioned organization, specify Recfm and Space values for directory blocks. See z/OS DFSMS Using Data Sets.

Table 1 summarizes which data class attributes apply to each record organization (RECORG).

Table 1. Applying Data Class Attributes to Record Organization (Recorg)
Attribute	Record Organization (RECORG)
Attribute	Blank	KS	ES	RR	LS
LRECL	x	x	x	x
RECFM	x
KEYLEN	x	x
KEYOFF	x	x
VOLUME COUNT	x	x	x	x	x
SPACE	x	x	x	x	x
CISIZE	x	x	x	x	x
FREESPACE	x	x
SHAREOPTIONS	x	x	x	x	x
Retpd or Expdt	x	x	x	x	x
DSNTYPE	x	x
COMPACTION	x	x

See the following for more information:

Keylen

Specifies the key length in bytes. To use this attribute, you must specify either KS or blank for the Recorg attribute. If the Recorg value is KS, the Keylen attribute represents the length of the KSDS key field and ranges from 1-255, or you can leave it blank. If the Recorg value is blank, the Keylen value ranges from 0-255, or you can leave it blank. For either value of Recorg, you must assign a value to the Keylen attribute that is less than or equal to the LRECL value.

Keyoff

Specifies the displacement from the beginning of a record to the KSDS key field. It is valid only when the Recorg value is KS. The Keyoff value can range from 0 to the value of (LRECL - Keylen).

If a Keylen value is specified, then the Keyoff attribute must also be specified, or 0 value is used. This value is merged only if the Keylen value is not specified in JCL.

CIsize DATA

Specifies the control interval size for the data component of data sets having Recorg values of KS, ES, RR,or LS. The default is 4096.

% Freespace

Specifies the percentage of each control interval and control area to be set aside as free space when the cluster is initially loaded or when a mass insert is done. It applies only to the data component. The Freespace attribute is valid only if the Recorg value is KS or blank. The default is blank.

Media Interchange

Provides the capability to control the type of media created to make the data and media acceptable to other processors in the same or different locations. For example, you can create a data class with a name of BOSTON and define the media interchange parameters (Media Type and Recording Technology attributes) compatible with the tape hardware in the Boston location. When the hardware in Boston is changed, the BOSTON data class can be changed to the new media interchange parameters.

Media Type

Specifies mountable tape media cartridge type. The valid media types are MEDIA1, MEDIA2, MEDIA3, MEDIA4, MEDIA5, MEDIA6, MEDIA7, MEDIA8, MEDIA9, MEDIA10, or blank. This field is optional.

Recording Technology

Specifies recording technology for mountable tape media cartridges. This field is optional and dependent on the value specified in the Media Type field.

If MEDIA1 is specified, either 18TRACK or 36TRACK is valid.
If MEDIA2 is specified, only 36TRACK is valid.
If MEDIA3 or MEDIA4 is specified, either 128TRACK or 256TRACK is valid.
If MEDIA5, MEDIA6, MEDIA7, or MEDIA8 is specified, EFMT1, EFMT2, EFMT3 and EEFMT3 are valid.
If MEDIA9 or MEDIA10 is specified, EFMT2, EFMT3, and EEFMT3 are valid.

Refer to z/OS DFSMS OAM Planning, Installation, and Storage Administration Guide for Tape Libraries for further information on data class attributes and the Recording Technology field.

Performance Scaling

Specifies the performance scaling preference. The valid values are Y, N, or blank. This field is optional.

If you select a value of Y, it means that you want performance scaling. Performance scaling, however, is valid only when you select MEDIA5 or MEDIA9. This value is not valid if you select any other media type. Also, the appropriate recording technology must be used for the selected media type.
If you select a value of N or blank, it means that you do not want performance scaling.

Performance scaling and performance segmentation are mutually exclusive.

Performance Segmentation

Specifies whether the system should enable segmentation format of the tape. The value specified in this field is considered only for the devices that support the segmentation for performance feature. The valid values are Y, N, or blank. This field is optional.

If you select a value of Y, it means that you want performance segmentation. Performance segmentation, however, is valid only when you select MEDIA5 or MEDIA9. This value is not valid if you select any other media type. Also, the appropriate recording technology must be used for the selected media type.
If you select a value of N or blank, it means that you do not want performance segmentation.

Performance segmentation and performance scaling are mutually exclusive.

Block Size Limit

Specifies the block size limit for new tape data sets on SMS and non-SMS managed storage. This value can be from 32760 - 2147483648, 32 KB - 2097152 KB, 1 MB - 2048 MB, or 1 GB - 2 GB. The default is blank.

When a program opens a tape data set without a block size value for output, the system determines a block size. This system-determined block size value is less than or equal to the first value in the following:

BLKSZLIM keyword on the DD statement or the dynamic allocation equivalent
Block size limit specified in data class (even for non-SMS-managed data sets)
TAPEBLKSZLIM keyword in the DEVSUPxx member of SYS1.PARMLIB
32760

Currently, OPEN chooses a block size value of no greater than 262144, or 256 KB. Any larger limit has no effect.