Sets the maximum size that the set_cachesize
                  parameter is allowed to set. 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 set_cachesize parameter.  If no value
                  is specified, it defaults to the initial cache size.
             
                 The syntax of this parameter in the
                 DB_CONFIG file is a single line with
                 the string set_cache_max, one or more
                 whitespace characters, and the maximum cache size in bytes,
                 specified in two parts: the gigabytes of cache and the
                 additional bytes of cache.  For example:
             
set_cache_max 2 524288000
Sets the maximum cache size to 2.5GB.
This parameter can be changed with a simple restart of your application; you do not need to re-create your environment for it to be changed.
For more information, see DbEnv::set_cache_max().