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As documented in the MVS JCL Reference, the general syntax for coding the SUBSYS on a DD statement for any subsystem is:
SUBSYS=(subsystemname,parameters)
The parameters for the CA Compress subsystem are broken into four pieces: subtype, fdtname, addname, and other-parameters. So, for the CA Compress subsystem, the syntax can be redefined as:
SUBSYS=(subsystemname,subtype,fdtname,addname, other-parameters)
Specifies the name given to your CA Compress subsystem when it was installed on your system. The usual name is 'ZSAM'.
This parameter must be the constant 'SHRK'.
Specifies the CA Compress compression algorithm or File Descriptor Table (FDT) which is to be used for the data set. The following values are valid:
Specifies the Super Express compression algorithm.
Specifies that CA Compress is to use one of the provided standard File Descriptor Tables (FDT). The 'xx' can be a number from 01 to 06.
Specifies the name of the compression algorithm or File Descriptor Table (FDT) created for your data set. The first character of this name must be alphabetic or the job fails with a JCL error.
Specifies the associated ddname which is to be used by CA Compress instead of dynamically allocating the data set. The associated ddname specifies the ddname of another DD statement coded in the step, which must allocate the data set to be processed. The DD statement where SUBSYS= is coded should normally contain only the SUBSYS parameter. All other DD statement parameters for the file should be coded on the associated DD statement. However, DSN and DCB must sometimes be coded on both DD cards because certain products like CICS can validate them during the OPEN process.
Using an associated ddname is the only way to specify certain DD statement parameters which are incompatible on a DD statement where SUBSYS= is specified (that is, DISP=PASS or for SMS-managed data sets). The addname parameter is positional, so a comma must be coded when it is omitted if other parameters follow it.
The DD statement referenced by the associated ddname is looked for when the data set is opened. If it is not found, CA Compress issues message ZSUR002I to inform you of the missing DD. The data set allocated by the associated ddname's DD statement can be of any type that is supported by QSAM.
Note: The associated ddname may also be needed to avoid I/O errors on concatenated SUBSYS data sets after the first. For an example on how to avoid this problem, see the CA Compress User Guide.
Specifies other parameters which control the operation of CA Compress. If an error is made in coding these parameters, a JCL error results. Each of the following parameters can be coded one time each in any order:
STD or STANDARD—Specifies that CA Compress is to use the standard File Descriptor Table (FDT). This parameter can be omitted if a File Descriptor Table of the name STDTBLxx is specified for the fdtname parameter (described above). See ADD Statement in the chapter Control File Maintenance Utility for more information about the STANDARD parameter.
SDB=YES or SDB=NO – Specifies whether the actual compressed data set should be written with BLKSIZE calculated using System Determined Blocksize (SDB). SDB=NO directs the compress not to optimize but to use the uncompressed BLKSIZE coded in the JCL or set in the Control File entry. If this is a PS data set, SDB= defaults to whatever was specified or defaulted for the Control File entry. If not, the default is YES unless NOSDB was specified on the started task. SDB= does not affect the BLKSIZE parameter of the SUBSYS data set, which must be nonzero to avoid SDB, and the BLKSIZE will continue to look to user programs like the JCL specification. Unless the compressed data is read as compressed with DCB specified, SDB=YES is best.
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