determines the number of objects in each slab this can easily be done by consulting reference count 305 of each header of a slab the first partially filled slab will be chosen to be squeezed the flag 325 in the header of the slab to be squeezed is set to squeeze a slab the invention iterates through the objects to determine which objects are actually allocated while doing so the page reference count array 320 is updated any allocated page that does not hold data for any of the objects will be disclaimed and the slab will be moved to the u201c full u201d list of slabs since no more data may be placed therein further if the application has supplied a callback function the objects in the slab that are still allocated are iterated over and the callback function is called with a reference to the object for each allocated object the callback function is free to do what it wants with the referenced object ideally the callback function can free the referenced object or mark it to be freed later config_callback is the command used by an application to provide a callback function as mentioned above a callback function is free to do what it wants with any referenced.