int Tcl_SetRecursionLimit(interp, depth)
At any given time Tcl enforces a limit on the number of recursive calls that may be active for Tcl_Eval and related procedures such as Tcl_GlobalEval. Any call to Tcl_Eval that exceeds this depth is aborted with an error. By default the recursion limit is 1000.
Tcl_SetRecursionLimit may be used to change the maximum allowable nesting depth for an interpreter. The depth argument specifies a new limit for interp, and Tcl_SetRecursionLimit returns the old limit. To read out the old limit without modifying it, invoke Tcl_SetRecursionLimit with depth equal to 0.
The Tcl_SetRecursionLimit only sets the size of the Tcl call stack: it cannot by itself prevent stack overflows on the C stack being used by the application. If your machine has a limit on the size of the C stack, you may get stack overflows before reaching the limit set by Tcl_SetRecursionLimit. If this happens, see if there is a mechanism in your system for increasing the maximum size of the C stack.