Eat up all the heap -- Still report segmentation fault?

I have an application which works fine for small data sets. (PathFinding) as the sets get larger the memory consumptions goes wild.

When I attempt larger data sets my problem halts with a "Segmentation Fault". Now obviously I've seen that error all to many times... But I am curious, if I run out of (Ram + Swap) will the program crash with the message still?

I am on a point between, there is a super minor memory leak in my code which is only exploited on large data sets. Or I am eating up the entire heap.