NCMPBUF parameter

Number of compression buffers

Summary

Default value

0

Parameter type

System

Where set

User 0 CCAIN parameters

Related products

All

Introduced

Before Sirius Mods 6.7

Description

This numeric parameter indicates the number of compression buffers to be allocated at initialization. It must have a value between 0 and 32767.

Since datastream compression and decompression requires a compression buffer, this parameter limits the number of simultaneous compression or decompression operations. If not set, no buffers are allocated and no compression or decompression is allowed. If all compression buffers are in use, a compression or decompression request waits for the next available buffer.

Since decompression and (especially) compression are very CPU-intensive operations, there is probably little benefit to having many such operations running at once. Adding to this the fact that compression buffers are quite large (over 300K bytes), suggests that it is best to use a relatively small value for NCMPBUF (like 10 or less).

Compression and decompression are used by:

• The Janus Web Server requests for which compression is requested (via the COMPRESS setting on JANUS DEFINE or JANUS WEB commands, or via the $WEB_SET function).
• The $inflate, $deflate, $gzip, and $gunzip functions.

For more information about the compression feature, see the $deflate, $inflate, $gzip, and $gunzip descriptions in the Sirius Functions Reference Manual, and see the description of the COMPRESS parameter of the JANUS DEFINE command in the Janus TCP/IP Base Reference Manual.