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From: dubner@hpspkla.spk.hp.com (Joe Dubner)
Newsgroups: comp.lang.c
Subject: Re: _stklen in Turbo C
Message-ID: <3920002@hpspkla.spk.hp.com>
Date: 6 Feb 91 15:59:35 GMT
References: <1921@ruunsa.fys.ruu.nl>
Organization: Hewlett Packard Company, Spokane, Wa.
Lines: 41

> For a variety of reasons I'd like to be able to compile (on a DOS machine
> with Turbo C) with a stack that is larger than the usual 4kB. The manual
> (yes, I *have* read the FM) says I should simply set _stklen (defined in
> dos.h) to the desired value. I just can't find out where. If I put e.g.
> 
>   _stklen = 10000;
> 
> at the start of main (), nothing happens, i.e. when I deliberately cause
> a stack overflow by some silly recursion, the number of times my
> stack-consuming function can call itself before triggering the `Stack
> overflow!' run-time error is always the same. (I can even make _stklen 0
> if I like.) Actually, I don't understand how a program would be able to
> change its own stack size at run time. Is this really what happens (or,
> in my case, doesn't happen)? Who has a working example of how to do this?


Chalk this up to a quirk (bug? Or design decision?) in TC++.  (I assume
you're using it -- I don't know about TC 2.0).  _stklen needs to be set
_outside_ of any function and _before_ any code is generated (before
your first linked function) if stack overflow checking is enabled (and I
assume it is in your case, judging by the 'Stack Overflow!' message).

For example:

extern unsigned _stklen = 16 * 1024;

main()
{}

other_functions()
{}

I'll bet this fixes it for you!

Joe

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Joe Dubner     K7JD  |  Hewlett Packard Company  |  dubner@hpspkla.HP.COM
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