Internal details: The large region is split into individual same-sized blocks of memory. On creation, we allocate a single block of memory that will always remain zero, and map that into the entire memory region. Then, the first time any of these blocks is written to, we swap the mapped zero block out with a newly allocated block of memory. On clear, we swap back to the zero block and deallocate the data blocks. That way we only actually allocate one zero block as well as a handful of real data blocks where the JitCache actually writes to.
Admiral H. Curtiss