Retrieves information about memory usage by user cache.
This function has no parameters.
Array of meta data about user cache memory usage or false on failure
The array returned by this function contains the following elements:
memory_total - amount of memory in bytes allocated for the user cache
memory_free - amount of free memory in bytes available for the user cache
num_used_blks - number of memory blocks used by the user cache
num_free_blks - number of free memory blocks available for the user cache
memory_overhead - amount of memory in bytes used for the user cache internal structures