Configuration Parameters › Destination Parameters for Single LUs, Groups of LUs, and Single IPNAMEs › COMPRESS

COMPRESS

This parameter specifies whether data compression is used for a transfer.

YES

CA XCOM Data Transport provides Run Length Encoding (RLE) only for blanks and binary zeroes.

NO

No data compression takes place.

RLE

CA XCOM Data Transport provides complete RLE for all repeating characters.

COMPACT

CA XCOM Data Transport provides complete RLE (as in RLE) plus a byte compaction scheme suitable for uppercase EBCDIC text.

COMPACTL

The COMPACTL compression parameter is the same as COMPACT. However, this value is most suitable for lowercase EBCDIC text.

LZSMALL

CA XCOM Data Transport compresses the data according to the small memory model of Lempel‑Ziv 77 compression.

LZMEDIUM

CA XCOM Data Transport compresses the data according to the medium memory model of Lempel‑Ziv 77 compression.

LZLARGE

CA XCOM Data Transport compresses the data according to the large memory model of Lempel‑Ziv 77 compression.

HUFFMAN

Greater compression than RLE but not as much as the Lempel-Ziv 77 modes.

LZRW3

General-purpose algorithm that runs fast and gives reasonable compression.

ZLIB(n)

Greater compression than LZRW3 but less than LZSMALL, LZMEDIUM, and LZLARGE. The n value can be 1 through 9.

Default: YES

Note: Specifying a value other than NO enables use of zIIP to perform the compression function. zIIP processing is used for compression only if the buffer size to compress is >= 4096 bytes. Specifying PACK=LENGTH and use a high MAXPACK value (>= 4096) for TCP/IP transfers or RUSIZE (>=4096) for SNA transfers to use zIIP.

COMPRESS_PDS

COMPRESS_PDS is the parameter that causes the actual PDS compression to happen. If your CA XCOM Data Transport administrator has enabled the programmatic PDS compression feature in a CA XCOM Data Transport region, you can use the COMPRESS_PDS option to control if and when output PDS data sets get compressed as part of the transfer.

NONE

Suppresses the compression of an output PDS dataset as part of a CA XCOM Data Transport transfer.

BEFORE

Compresses an output PDS dataset before the transfer of user data begins.

AFTER

Compresses an output PDS dataset after the transfer of user data has completed.

BOTH

Compresses an output PDS dataset both before and after the transfer of user data.

Default: NONE

Notes:

• COMPRESS_PDS applies only to PDS data sets that is, or have been, opened for output as the target of a CA XCOM Data Transport transfer.
• If the COMPRESS_PDS option is present in the DEST member for a particular transfer partner, and that DEST member is made available to the XCOMJOB utility that is used to schedule a transfer to that partner, it becomes the default value for all transfers initiated with that partner CA XCOM Data Transport in that invocation of XCOMJOB.
• If your CA XCOM Data Transport administrator configures CMPRS_PDS_ALLOW=YES or CMPRS_PDS_ALLOW=X37, the COMPRESS_PDS=NONE option cannot suppress the compression of an output PDS data set if a z/OS system abend B37, D37, or E37 occurs.

Output

Output from the compression utility is handled in accordance with the setting of the CMPRS_SYSOUT_CL server-level parameter. The spool data sets (if they are allocated) will have the following prefixes:

• XB for compressions performed before a transfer, as in the case with COMPRESS_PDS=BEFORE or on a restarted transfer request
• XA for transfers performed after a transfer

The decimal transfer request number is appended to the prefix to provide a unique spool entry for each compression operation. This naming convention allows for the correlation of compression utility output with a specific file transfer if there is a need for problem determination research after the transfer.

Example:

For a request number 034271, the following spool entry names would apply:

• The output from the utility used to compress the PDS data set before the transfer would be named XB034271.
• For a compression performed after the data transfer, the SYSOUT dataset would be named XA034271.