<?php print_r(apc_sma_info());?>
The above example will output something similar to:
Array ( [num_seg] => 1 [seg_size] => 31457280 [avail_mem] => 31448408 [block_lists] => Array ( [0] => Array ( [0] => Array ( [size] => 31448408 [offset] => 8864 ) ) ) )