I want to host 3 web sites in one physical server(1G ram) along with resin. JDK is Sun 1.4

I need assign each of them different JVM size they could use. for instance, site A could use 256M, site B could use 128M, site C could use 128M too. My question is where to set them? I have checked resin.conf and Apache httpd.conf, nothing found.

my another question is, the above said JVM is so-called private JVM? if site A is down, any effect on other 2 sites? I don't hope site B and C will be affected.

Thanks.