HP shared memory limits

OK large-scale HP people, here's a challenge: HP-UX 10.20 supports up to 1.75 GB shared memory per Informix engine instance, carve it up as you will. Suppose I created such a system on a large HP box. Could I then create a second similarly large instance on the same box/OS image? A third? Anybody know where I'd hit architectural limits?? Nevermind the advisability or operational problems of doing so, I don't plan to actually do it, but I need to know where the limits are. Many Thanks - Greg