The IQ Buffer Cache Size options, as well as other options you can set once the server is running, determine how much memory is available.
The default IQ buffer cache sizes of 16MB for the main buffer cache and 8MB for the temporary cache are too low for any active database use.
(Recommended) To set buffer cache sizes server-wide for the current server session, specify the database startup utility start_iq options -iqmc (main buffer cache size) and -iqtc (temp cache size).
To set cache sizes for a database, use the sa_server_option stored procedure with main_cache_memory_mb or temp_cache_memory_mb parameters.
If you set IQ buffer cache sizes higher than your system can accommodate, however, SAP Sybase IQ cannot open the database.
The server options (-iqmc and -iqtc) also let you use as much memory as your system allows, the only limit being the amount of physical memory on the machine. For this reason, on 64-bit systems, use -iqmc and -iqtc, which do not override the settings made by sa_server_option.
The cache sizes set by -iqmc and -iqtc apply to all databases started until the server is shut down. So, for example, if you set both -iqmc and -iqtc to 500 (MB) and start one database at server startup and another database later on the same server, you need at least 2GB available for the two main and two temp caches.