As I mentionned above, this is a hack to try and prentent the memory is used. You should not need to do it and it can have side effects because this is not what the allocator is made for!
In particular, if any allocation fails due to fragmentation, we dealloc and realloc memory to reduce fragementation. But since the whole memory was allocated at once, this is not possible after this hack and so it will OOM even though it will work without it.
Here again, @dragen  why do you need to do this?