|
|
|
After a file is Prepassed, all or part of the file can be compressed by the SHRINK Compression Utility, which also prints compression statistics. The utility supports only custom compression using an FDT, not Standard Tables, Hardware Compression, or Super Express.
The SHRINK Compression Utility is invoked by executing the program named SHRINK and supplying a PARM value in the form C=xxx (xxx is either the word ALL or a three-digit number). ALL causes the entire data set defined by the INFILE DD statement to be compressed. A three-digit number indicates, in thousands, the number of logical records to compress from the data set defined by the INFILE DD statement.
Member SHR2CMP2 uses a load module FDT, which is defined by allocating its load module library in STEPLIB and specifying its name using the FN= keyword in the PARM. In both cases, INFILE is the data set to be compressed and OUTFILE is the compressed data set.
The SHRHCCMP Compression Utility is invoked by executing the program named SHRHCCMP and supplying a PARM value in the form:
DICT=dictname,C=xxx,N=nnn
where xxx is a three-digit count in thousands of records to compress or ALL and nnn is a three-digit noncompressible length. The defaults are C=ALL and N=000. You can omit either one or both of these defaults. DICT= is always required.
For both Compression Utilities, the OUTFILE LRECL should be at least eight bytes greater than the INFILE LRECL, 12 bytes greater if the uncompressed file is non-VSAM fixed length in order to provide for the RDW in the compressed records. In most cases, DCB parameters in the output data set can be defaulted.
| Copyright © 2012 CA. All rights reserved. |
|