Discard file record layout

This section describes the record layout of the discard file. This file is generated when the EXCEPTION_LIMIT keyword and the DISCARD_FILECTL subcommand are specified with a command process.

Related topic

Layouts

Important

A user-written program will need to be created to process the discarded data.

Discard file record layout 1: DMCB definition contains the record layout for the DMCB definition.

The first record in this file contains database definition information.

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Field name	Size	Description
LL	H	Standard RECFM=V record length
ZZ	2X	Standard RECFM=B record flags
exception	CL4	Binary zeros (LOW-VALUES)
identifier	CL4	'DMCB'
max ckeyl	H	Maximum concatenated key length for database
IMS level	2X	IMS release level
filler	16X	Binary zeros (LOW-VALUES)
DMCB	variable	IMS DMCB header for the database Important This format is defined by the DBFDMCB macro, and might change between IMS releases.

Discard file record layout 2: SDBF definition contains the record layout for the SDBF definition.

The next set of records in this file contains segment definition information--one record for each segment type that is defined in the database.

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Field name	Size	Description
LL	H	Standard RECFM=V record length
ZZ	2X	Standard RECFM=B record flags
exception	CL4	Binary zeros (LOW-VALUES)
identifier	CL4	'SDBF'
filler	20X	Binary zeros (LOW-VALUES)
SDBF	variable	IMS SDBF for the segment Important This format is defined by the DBFDMCB macro, and might change between IMS releases.

Discard file record layout 3: segment data contains the record layout for the segment data.

There is one record for each discarded segment following each of these header records.

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Field Name	Size	Description
LL	H	Standard RECFM=V record length
ZZ	2X	Standard RECFM=B record flags
exception ¹	4C	Exception code
segcode	H	Segment code
seglevel	H	Segment hierarchical level
ckeyl	H	Concatenated key length for this segment
segll	H	Segment data length
segname	CL8	Segment name
filler	8X	Binary zeros (LOW-VALUES)
ckey ²	CLn	Concatenated key
segdata ³	variable	Segment data
^{1 For a list of exception codes and descriptions, see Exception codes.} ^{2 The size of the ckey field is fixed based on the maximum length for the concatenated key in the database. For more information, see the max ckeyl field in the DMCB definition record in Discard file record layout 1: DMCB definition. The length of the ckey field is the smallest multiple of eight that is greater than, or equal to the maximum length of the concatenated key for any segment in the database. When the actual length of the concatenated key is less than the maximum length, unused bytes in ckey field will be filled with binary zeros (LOW-VALUES).} ^{3 The segment data is written in the same form as it appears in the I/O area of an application program. As a result, any compressed data sets will be expanded, variable length segments will contain the 2-byte field, and the fixed length segments will not contain a length field.}

Exception codes contains a list of exception codes, along with a description of each code.
The exception code field (see Discard file record layout 3: segment data) contains a 4-character code, indicating the type of exception that caused the segment to be discarded.

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Code name	Description
zeros	None (LOW-VALUES) This is a header record.
blanks	None This segment is a dependent of a segment for which an exception has been detected.
DUP	Duplicate key
AREA	Target output area not in OAREA list (root segment only)
RAND	Randomizer error (root segment only)
SEQ	Key sequence error
MINL	Segment length less than the minimum
MAXL	Segment length greater than the maximum

Discard file record layout

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