DSET segment type format

The IMS catalog DSET segment type contains metadata about a data set group specification for an IMS database.

The information in this segment is generated based on the parameters of the DATASET statement of the DBDGEN utility. All DBD catalog records have at least one child DSET segment instance.

Segment name: DSET
Parent name: DBD
Sequence field: DSETSEQ
Segment length: 96 bytes

Table 1. DSET segment type format
Offset (bytes)		Length (bytes)	Data type	Field name	Description	Unique key field
1		2	X	LEN	Length of this segment
3		2	X	CTL	Control field
5		2	X	DSETSEQ	Sequence field, type = U	X
	5	2	X	SEQNUM	Sequence number
9		8	C	DD1	The name of the first data set in this data set group. For HSAM, SHSAM and GSAM databases, this field is the name of the input data set. For HISAM. SHISAM and INDEX databases, this field is the name of the primary data set. For Fast Path databases, this field is the name of a defined data area. MSDBs and logical databases do not use this field.
17		8	C	DD2	The name of the output data set for HSAM, SHSAM, and GSAM databases. If no name is specified for a GSAM database, DD1 is used as the output data set.
25		8	C	OVERFLOW	The name of the overflow data set in this group.
33		2	X	BLOCK1	Blocking factor 1 for the data set group. See the DATASET statement of the DBDGEN utility for usage information.
35		2	X	BLOCK2	Blocking factor 2 for the data set group. See the DATASET statement of the DBDGEN utility for usage information.
37		2	X	SIZE1	Block size 1 for the data set group. See the DATASET statement of the DBDGEN utility for usage information.
39		2	X	SIZE2	Block size 2 for the data set group. See the DATASET statement of the DBDGEN utility for usage information.
41		2	X	RECORD1	Record size 1 for the data set group. See the DATASET statement of the DBDGEN utility for usage information.
43		2	X	RECORD2	Record size 2 for the data set group. See the DATASET statement of the DBDGEN utility for usage information.
45		2	X	SCAN	The number of DASD cylinders that are scanned for free storage during a segment insert operation. Used only for HIDAM and HDAM databases.
47		2	X	SEARCHA	The type of algorithm used to search for free storage during a segment insert operation. Used only for HIDAM and HDAM databases. The different type codes and meanings are: 0 IMS chooses which algorithm to use. 1 IMS does not search for space in the second-most desirable block or control interval. 2 IMS includes a search for space in the second-most desirable block or control interval.
49		2	C	RECFM	The format of records in this data set group for a GSAM database: F Fixed-length FB Fixed-length and blocked V Variable-length VB Variable-length and blocked U Undefined length
51		2	X	FRSPFBFF	The number data blocks per block of free space that are allocated in an HDAM or HIDAM database.
53		2	X	FRSPFSPF	The minimum percentage of free space in each control block or interval in this data set group. Used only for HDAM and HIDAM databases.
55		8	C	REL1	The terminal relationship type and segment ownership type in an MSDB: NO Non-terminal-related without terminal keys TERM Non-terminal-related with the LTERM name as the key FIXED Terminal-related with the LTERM name as the key, with segment insertions and deletions disabled DYNAMIC Terminal-related with the LTERM name as a key, with segment insertions and deletions enabled
63		8	C	REL2	The name of the pseudo-sequence field for a keyed MSDB. Segment search arguments can use the name of this pseudo-field and the LTERM name as the key value.
71		26	C	FILLER	Reserved