user manual

56 IBM Sterling Connect:Direct for i5/OS User’s Guide
COMPRESS(*NO | *YES| *EXT | X\xx\ | C\cc\ )
specifies that the data is to be compressed, which reduces the amount of data transmitted as the file is
copied from one node to another. The file is automatically decompressed at its destination unless
DECOMP(*NO) is specified in TOSYSOPTS.
You should specify the primary compression character for text data or single-character repetitive data.
Extended compression generally offers improved compression for all types of data.
*NO
specifies no compression.
*YES enables compression. If *YES is specified, the default primary compression character is
PRIMEchar=X\40\ (hex 40=“ ”).
If you specify *YES, Sterling Connect:Direct reduces the amount of data transmitted based on the
following rules:
 Repetitive occurrences (2–63) of the primary compression character are compressed to one byte.
 Repetitive occurrences (3–63) of any other character are compressed to two bytes.
X\xx\ enables compression, where xx is the hexadecimal representation of the value to be used for the
primary compression character.
C\cc\ enables compression, where cc is the character representation of the value to be used for the
primary compression character.
*EXT specifies that extended compression is used to search for repetitive strings of characters in data
and compress them to codes that are transmitted and converted back to the original string during
decompression. Specify this parameter when line transmission speeds are limited, the CPU is
available, and data is repetitive.
CRC(*INITPARMS
|*NETMAP|*OFF|*ON)
Determines whether node and Process statement overrides for Cyclic Redundancy Check (CRC) are
allowed. If this value is set to *OFF, setting overrides for CRC checking will be ignored. The default
value is *INITPARMS.
*INITPARMS
specifies that the CRC setting is determined by the value for the initialization
parameter TCP.CRC.
*NETMAP specifies that the CRC setting is determined by the value for the NETMAP parameter,
Cyclic Redundancy Check. The value for the initialization parameter TCP.CRC must be set to *ON
and the value for the initialization parameter TCP.CRC.OVERRIDE must be set to *YES.
*OFF specifies that CRC is disabled.
*ON specifies that CRC is enabled.
ECTUNING (ecclevel,ecwinsize,ecmlevel)
ECCLEVEL specifies the extended compression level, which affects how much CPU the extended
compression routines use. Higher compression levels use more CPU but achieve greater compression.
The valid values for this subparameter are 1–9, inclusive. The default value is *INITPARMS.
ECWINSIZE specifies the extended compression window size, which is specifically for the history
buffer that is filled from the user’s input buffer ( both compressing and decompressing). The window
specifies the amount of storage designated to maintain data previously read.
Note: Compression is CPU-intensive. Its effectiveness is dependent on the data and line speed and
should be used only if it benefits the installation.