Config.sys is not used in XP - I take it you have read to increase the Stacks in the config.sys file??
XP handle the stack automatically from memory - "stacks are just an amount of memory that a program requires for remote procedure calls - if the program has been written incorrectly this error may occur - or simply there is an out right bug in the program - but if you want to change the stacks them goto Systems Properties - then advanced - then environmental variables (at the bottom!) - then add to systems variable and then add stacks 9,512 - I suggest though that there is more likely a bug in the program which has resulted in a stack overflow as oppose to not enough stack space.
Peter