It seems from experimenting that no matter what, if you want to use a map you have to initiate the map in someway before runtime, either through setting maxx and maxy or actually creating a map. If you do this then you can adjust these variables during runtime to change the maps size.
Example (This works):
However, if you don't setup a map at runtime, there is nothing you can do to initialize the map.
Example (this doesn't work-no map initialization):
Now I know this isn't a big deal and I can work around any issue with this. I am just wondering out of curiosity if there is a way to initialize a map at runtime.