IAMRECVR – DECOMPRESS Command

Recovery of Data that is Compressed

The IAM file recovery program, IAMRECVR is able to read sequential files created with the BACKUPCOMPRESSED feature, and write out a sequential file with the data uncompressed. This may be useful for when an application program needs to read the sequential file from FDRREORG or IDCAMS REPRO of the IAM file. This is facilitated with the new command, DECOMPRESS.

DECOMPRESS Command Statement

The DECOMPRESS command allows a compressed backup of an IAM file to be decompressed in the event that IAM is not available. The IAM VSAM Interface (VIF) does not have to be active.

IAMRECVR DECOMPRESS Command Operands

   DECOMPRESS
       [ FROMDDNAME= ddname ]   ,KEYLEN= nnn
       ,RKP=nnnnn          [,SCAN]
       [,TODDNAME= ddname ]

DECOMPRESS Command Operands

The table below contains descriptions of the keywords for the DECOMPRESS command of IAMRECVR. The minimal abbreviation for each operand keyword is underlined.

Keyword	Description
FROMDDNAME=	Defines the DDNAME of the compressed IAM backup file. The default is DISKIN.
KEYLEN=	Required operand that specifies the length of the key within the data records in the IAM file. This value can be obtained from an IAMINFO or LISTCAT report on the original IAM data set.
RKP=	Required operand that specifies the relative location of the key within the data record in the IAM file. This value can be obtained from an IAMINFO or LISTCAT report on the original IAM data set.
SCAN	Allows a compressed backup file to be read and all records decompressed, but an output file will not be created. SCAN can be used to verify a compressed backup file.
TODDNAME=	Defines the DDNAME of the output uncompressed flat file. The default is TAPEOUT.

EXAMPLE A: DECOMPRESS

Assume an IAM file with 100 byte records, an 8 byte key length with a relative key position (RKP) of 10 has been backed up by an IDCAMS REPRO with the BACKUPCOMPRESSED option, and is now needed in its uncompressed state.

Example of JCL and Control Card for Decompress (EX4504A)

//DECOMPRS EXEC PGM=IAMRECVR
//SYSPRINT DD SYSOUT=*
//DISKIND DD SN=my.seqfile,DISP=OLD
//TAPEOUT DD DSN=my.uncomp.seqfile,DISP=(,CATLG),
//DCB=(RE CFM=VB,LRECL=104,BLKSIZE=32760),UNIT=TAPE
//SYSIN DD*
DECOMPRESSKEYLEN=8,RKP=10
/*