the first column is a number out of the hat the second number is normally twice the size of the first number so lets say i want a map with a width of 200 tiles the first number would be 100
MAP_SIZE_GIGANTIC 100 200 2
i think if you replace the normal one with that you should get a ultra gigantic map
Just be careful there is a limit to the map size if you want a random one( the map goes funny) I think it is a bout 210 or something but for custom maps there is no limit