#include <db.h>

int
DB_ENV->set_cache_max(DB_ENV *dbenv, u_int32_t gbytes, u_int32_t bytes);  

The DB_ENV->set_cache_max() method sets the maximum cache size, in bytes. The specified size is rounded to the nearest multiple of the cache region size, which is the initial cache size divided by the number of regions specified to the DB_ENV->set_cachesize() method. If no value is specified, it defaults to the initial cache size.

The database environment's maximum cache size may also be configured using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "set_cache_max", one or more whitespace characters, and the size in bytes. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

The DB_ENV->set_cache_max() method configures a database environment, not only operations performed using the specified DB_ENV handle.

The DB_ENV->set_cache_max() method may be called at any time during the life of the application.

The DB_ENV->set_cache_max() method returns a non-zero error value on failure and 0 on success.