What about using slots?

Craig Hicks

This would be somewhat problematic. Potentially, there could be a >> mechanism for having a different "stack" for each thread. Suggestions on >> how this could be achieved are welcome :)

>Policies?  multi-threaded version has a container of allocators, hashed on 
>the thread ID?  A faster alternative would be to require the user to 
>specify which stack they want.  Both could be accomodated with something