This read-only integer reports the amount of memory held in the page (disk) cache, minus swap cache. An admin interprets a large cached value as generally healthy since Linux uses spare memory to cache disk data for performance, and this memory can be reclaimed if applications need it. For example, an admin alarmed by a low cpqLinOsMemFree value would check this cached figure to confirm most of the 'used' memory is actually reclaimable disk cache rather than truly unavailable.