UPInt Granularity;
Granularity represents the smallest block size that the heap will request from the "root" heap memory system, which ultimately routes to SysAlloc/SysAllocPaged. In other words, this is the size multiple by which the heap will grow. For example, with the default value of 16K, the first allocation of 10 bytes on the heap will allocate a 16K block; from that point on all of the further heap allocations will be serviced from that block until it is exhausted. Once exhausted, an additional block of granularity will be allocated. If all of the allocation within a block are free, it will similarly be returned to root heap manager for reuse in other heaps or returned to SysAlloc.