* Returns the size the region should have to enforce the memory limit.
* This will either be the original value of size, a truncated value,
* or zero. If the returned value of size is 0 the region should be
* Returns the size the region should have to enforce the memory limit.
* This will either be the original value of size, a truncated value,
* or zero. If the returned value of size is 0 the region should be