This week's book giveaway is in the Reactive Progamming forum. We're giving away four copies of Reactive Streams in Java: Concurrency with RxJava, Reactor, and Akka Streams and have Adam Davis on-line! See this thread for details.
Unless the "55555" is an actual number (and not just for testing) you could also try bumping up the JVM memory. Its default allocation is a LOT smaller than what most desktops and servers have available in unused memory.
Using Oliver's approach will probably give you more peace of mind, though :-)