Memory Management

[Shiraz]

I am trying to set aside some memory for my cache (hash/array etc) in
my script.
I use the ulimit and then monitor used mem with Devel::Size and
destroy when i am close to my limit. Any ideas on how to do this
better? Can anyone please point me to a memory management routing
that
is better than what i am using, specifically something that reserves
memory for the script explicitly and does not let it over flow ( no
out of memory errors )
Thanks