The default configuration is a special case. They are all in a stable orbit around the common barycenter, always forming an equilateral triangle. We actually have closed form solutions for this kind of configuration.
These are meta-stable, in that only a perfect initial state (positions and velocities) will be stable. Even then, I expect quantum uncertainties would kick in at some point. (In the simulator, the default system goes unstable at about 500 seconds, probably due to the limits of floating point math.)