A method, apparatus, and article of manufacture provide the ability to efficiently and effectively manage memory. A tri-linked list/tree of deallocated memory units available for use by a heap are used. A first link points to units smaller than a current block size, a second link points to units equal to the current block size, and a third link points to units larger than the current block size. When a request for memory is received, the tree is traversed to find a unit that satisfies the request and the appropriate unit in the free list is allocated.