It's amazing how I couldn't get a straight answer on this. We've had several of our Traveler servers become unresponsive with Xpages:out of memory errors and I couldn't understand why if Traveler started up its own JVM. I had increased the Traveler maximum memory size to 4096MB when we upgraded to Domino/Traveler 9. The server has 16GB of RAM which should be plenty then.