This variable controls data compression by the internal socket layer. Setting this variable to "ZLIB" means that data is compressed using the same algorithm as the gzip compression utility. A value of "RUNLENGTH" means that a simple compression based on counting repeated bytes of data is performed. RUNLENGTH compression tends to be faster than ZLIB compression, but tends not to compress as well, especially with large blocks of data. The default value for this variable is "NONE".

AGS_SOCKET_COMPRESS must be set before any socket communication is performed, and it cannot be changed via the SET ENVIRONMENT statement.

See File Compression for tips on how to use this variable in a thin client environment.

Note that Windows supports ZLIB compression, but not all UNIX machines do. If ZLIB compression is not supported on a particular machine, a variable value of "ZLIB" will be ignored. When the system must negotiate the compression algorithm to be used with a server, the method that both machines support is used.