Is there any way to increase string space?

Hey everyone. The program I'm writing uses string space like crazy. It's a tile based RPG and the fastest way that I've found to draw the tiles is to put all the tiles of one area into a string array and then DRAW them. Each string for each tile can be 2000 - 5000 bytes in length and when there's 20 or so of these for each map area, it chews up string space pretty quick.
I'd like to add more tiles to each area, mainly for variety, but I'm out of string space. Is there any way to increase how much space I can use?


I've also tried having the program access each tile file individually and load it from the file the moment it draws it. It works just the same (and doesn't take any memory) but the time it takes to load from a file slows down the program and makes screen scrolling sluggish. I've also just tried putting each tile into a GET and PUT type array, in which they would take up much less space than how I have them now, (each tile is a 20x20 pixel), but the problem is it's a smooth scrolling map, so as a tile moves off screen, eventually there will be an error when the program tries to PUT only half of a tile.

(If anyone knows how to PUT graphics out of the view screen area, that would be great too.)

Thanks!