The easiest way to set the stack size from .NET 2.0 and Win XP onwards is to spawn a new thread with the stack size you’d like:-
using System.Threading;
Thread T = new Thread(threadDelegate, stackSizeInBytes);
T.Start();
To change the stack size of the entire program you’d have to use editbin:-
EDITBIN.EXE /STACK:<stacksize> file.exe