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The ALTER statement for Physical Sequential changes the compression attributes of a data set or pattern that is currently defined to CA Compress.
ALTER {PSDSN=datasetname}|{PSPATTERN=patternname}
{,SUPEREXP|FDT=fdtname,[STANDARD]|DICTIONARY=dictionary}
{,DCBMODEL=datasetname}|{,RECFM=recfm,LRECL=lrecl,BLKSIZE=blksize}
{,RECFM=recfm,LRECL=lrecl,BLKSIZE=blksize}
{,EFFDATE=yyddd}|{ANYDATE}
[,GDG=YES|NO|ONLY]
[,SDB=YES|NO]
[,ERASEUNCAT=YES|NO]
[,EXCLUDE=YES|NO]
[,NEWNAME=newdatasetname]
[,NON-COMP=#]
[,UEXIT=YES|NO]
[,FORCE]
Specifies the physical sequential data set entry being ALTERed.
Specifies the physical sequential data set name pattern being ALTERed. The pattern can contain any character that is valid in a data set name along with the special characters ?, !, and /. These special characters are defined in the section Syntax Rules in this chapter.
Selects the type of compression desired for the data set or pattern being ALTERed.
The optional parameter STANDARD can be specified only in conjunction with the FDT=fdtname parameter. It informs CA Compress that the FDT specified should provide the compression or expansion tables only, and that the RDL specified in the FDT should be ignored. The STANDARD parameter allows one FDT to be used for a number of data sets that can share character distribution characteristics but not different noncompressible area. STANDARD is implied if the FDT parameter specifies a name of the form STDTBLxx where xx is a numeric value from 01 thru 06. The DICTIONARY parameter can specify a CA-supplied IBM Hardware Compression dictionary of the form HC#STDxx (where xx is numeric 01 to 05).
SUPEREXP specifies the low-overhead compression algorithm called Super Express.
RECFM=recfm; LRECL=lrecl; BLKSIZE=blksize
These parameters change the DCB attributes of the uncompressed data. These attributes must be kept in the Control File because they are unavailable elsewhere.
RECFM, LRECL, and BLKSIZE change each individual attribute.
You need not change them all, but the result after your specified changes must be a valid combination of RECFM, LRECL, and BLKSIZE for the data set. A consistency check is performed. If in combination they are invalid, the statement is rejected. For these values to be correct is vital.
DCBMODEL is ignored when an entry already has DCB attributes defined. For this reason, it has no effect on the ALTER statement except on PS Patterns for which no DCB attributes were defined when the Pattern was added.
These parameters are optional and mutually exclusive.
EFFDATE specifies the Julian date that compression is to be implemented on the data set. When the date becomes current or past, the data set is compressed the next time it is created or replaced.
ANYDATE specifies that the data set should be considered compressed already. If it is opened for output, compressed data is written, and if it is read, each record will be expanded. ANYDATE should be specified when you are implementing a data set already compressed in an earlier release of CA Compress using the SUBSYS JCL parameter; otherwise CA Compress expects to read uncompressed records until the data set is recreated, and applications receive compressed data.
Specifies whether pattern matches should be recognized for all data sets including GDGs (GDG=YES), excluding GDGs (GDG=NO), or only for GDGs (GDG=ONLY).
Specifies whether compressed data set BLKSIZE should be calculated by the IBM System Determined Blocksize (SDB) facility or set to the uncompressed data set BLKSIZE. SDB=YES gives better compression and I/O performance, but may cause I/O errors if a smaller BLKSIZE is coded on JCL which reads the compressed data set without CA Compress. The input BLKSIZE should never be coded except when using SUBSYS to invoke CA Compress, but until such JCL is corrected, SDB=NO will make it work correctly. The default is YES unless NOSDB is specified in the CA Compress started task JCL.
Specifies whether the entry should be purged from the Control File when the data set is uncataloged. This is an optional parameter, but it interacts with the GDG parameter. For instance, if ERASEUNCAT=NO and you specify GDG=ONLY, ERASEUNCAT is changed to YES unless you explicitly say ERASEUNCAT=NO.
Specifies that the data set is excluded from compression (YES), or no longer excluded from compression (NO).
Specifies the new data set name or data set pattern for a previously defined entry. This parameter can be specified in conjunction with any other parameters when renaming a PS data set or pattern entry.
Specifies a noncompressible area at the beginning of each record for other than custom Huffman or Tailored RDL methods. This parameter is especially helpful for setting aside noncompressible bytes to enable record selection or other processing on the data set without having to expand and compress records. The Utility rejects this parameter if the data set is already compressed.
Specifies whether data set should be considered defined as compressed only under CICS (SCOPE=CICS) or always (SCOPE=ALL). This parameter is primarily intended as a conversion aid.
Specifies whether data set should be considered defined as compressed only if on tape (DEVTYPE=TAPE), only if on direct access (DEVTYPE=DA), or anywhere.
Reactivates compression for this data set if compression has been inhibited due to an earlier error, usually a DCB parameter mismatch. The most common reason for CA Compress to inhibit an entry is that a compressed data set was expected, but the data set was actually uncompressed, perhaps because an uncompressed data set was renamed to this compressed data set name. This condition is normally corrected when the data set is recreated.
If the data set is correctly compressed, but the entry was inhibited due to a JCL error, an earlier CA Compress logic error, or some other condition, UNINHIBIT restores compression and expansion to the data set without having to recreate it. If the error is due to having used the wrong DCBMODEL data set or coding one of the other DCB parameters incorrectly in the Control File entry, you should correct these at the same time.
Specifies whether the Transparency User Exit is to be invoked during compression and expansion of each record.
Allows ALTER to be done even if the data set is already compressed. Valid uses include changing values such as the noncompressible area on a new entry created from an existing entry by the COPY statement, which can appear compressed even though it is a new entry. Misusing this parameter can cause compressed data not to expand, or can cause new records to be compressed differently from those already compressed in the data set.
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