how limit the maximum memory allocated to a task?

[tom arnall <kloro@cox.net>]

How do I limit the maximum memory allocated to a task. I have tried 'ulimit -m 
100000' on my 512MB system, but the task i'm dealing with is, according 
to 'top', still allocated about 98% of memory, bringing the system to its 
knees.

Thanks,

Tom Arnall
north spit, ca