memory Problem

Hi ,

One of java programs in our machine allocates 256M of heap memory and max of 512 memory(Tomcat to be specific).

Our ulimit per process is 32M.How can a process allocates such a big amount of memory

ps v output is

PGIN SIZE RSS LIM TSIZ TRS %CPU %MEM COMMAND
24 220776 220892 32768 22 28 1.9 11.0 /usr/ja

i am sure it's not shared memory kind of thing

And also

One more instance of Tomcat will consume 256M or will it use
existing Processes's memory

Any clarifications ?

Thanx in advance
Ganti