Must be left blank or set together with heapNewSize. If left blank a sensible value for the available amount of RAM and CPU cores is calculated.
Override to set the amount of memory to allocate to the JVM at start-up. For production use you may wish to adjust this for your environment. MAX_HEAP_SIZE is the total amount of memory dedicated to the Java heap. HEAP_NEWSIZE refers to the size of the young generation.
The main trade-off for the young generation is that the larger it is, the longer GC pause times will be. The shorter it is, the more expensive GC will be (usually).