_freeList
_freeList();
void _freeList();
_fullness(0), _freeList(NULL), _owner(o), _next(NULL), _prev(NULL)
b->setNext(_freeList);
_freeList = b;
block *_freeList; // A pointer to the first free block.
if (_freeList == NULL) {
block *b = _freeList;
_freeList = _freeList->getNext();
b->setNext(_freeList);
_freeList = b;