Is this of any help?
http://fox.wikis.com/wc.dll?Wiki~ManualGarbageCollection~VFP

>I'm hoping someone knows how to force VFP to do garbage collection.
>For example, on an NT machine with task manager watching the VFP memory allocated, I type:
>
>x = space(16777184) ' VFP allocates between 20-36meg of RAM
>x = Null
>Release x ' RAM stays allocated
>
>CLOSE ALL
>CLEAR ALL ' No luck - still allocated
>
>Is there any way to force memory allocation? SYS(3050) has
>no effect on this kind of memory allocation.
>
>We have a citrix box with many VFP apps running, and if one
>user runs a VFP routine which needs RAM, the RAM is staying
>allocated to that user indefinitely, slowing the other users
>down.
>
>If anyone has any insites, I would be very thankful.
>
>TIA,
>Ed