The method currently does not support the optional (and subject to change) type parameter for the stats command:
- "items", "sizes", "slabs"
The documentation for the optional parameters can be found here (sections below General-purpose statistics):
http://code.sixapart.com/svn/memcached/trunk/server/doc/protocol.txt
The Memcache Extension can be uses to retrieve that information:
http://www.php.net/manual/en/function.memcache-getstats.php