 handle of the block; it returns a pointer to the start of the block on the heap. If the block has been discarded, <CODE>
MemLock()</CODE>
 returns a null pointer.</P>
<P>
<A NAME="IX_MemUnlock()">
 </A>
Immediately after you are done using a block, you should unlock it by calling <CODE>
MemUnlock()</CODE>
. It is better to lock and unlock the same block several times than to retain control of it for an extended period, as locked blocks degrade the performance of the heap compaction mechanism. To unlock a b