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 DB_ENV->set_cache_max().