Re: About stack

[Guillaume Poletto <poletto at jeuxvideo dot com>]

Hi Brian,

Okay, the "limit" command says that stack is 8Mb long. Yes that's really 
enough in my case. My programs are mono-threaded, i don't use recursion 
and the functions that have big local variables don't call each other.

Well i write CGIs in C, and i thought that a program with big data 
segment takes more time to be loaded.

Thank you

Brian Budge a écrit :

> Hi Guillaume -
>
> In general, stacks are limited, and usually the limit is defined by
> the operating system.  On linux, you can type "limit" to see what your
> current limits are.  "unlimited" means that the OS will allocate as
> much as it can for your program's stack.
>
> If you have large stack variables, and there are a lot of function
> calls (recursion being a big no-no in cases like this), you will
> likely run out of memory.
>
> Why do you need it to be on the stack?  I'm guessing if you had it in
> the data segment before, you don't need to worry about trampling the
> memory (single thread access, no recursion), so you could allocate it
> on the heap at startup, and deallocate on shutdown of your program.
>
>  Brian
>
> On 3/8/06, Guillaume Poletto <poletto@jeuxvideo.com> wrote:
>  
>
> > Hello,
> >
> > I'd like to know what happens when using big local variables
> > ex :
> > void func () {
> > char mybuff[50000];
> > /* .. */
> > }
> >
> > To avoid problems, i have been used to put instinctivly big local
> > variables as 'static' in order to use data segment instead of stack. But
> > now i'd like to save memory on data segment and reconsider using stack.
> >
> > Is the stack limited? Is it configurable? Does some dynamic allocation
> > occurs (allocating more stack space)?
> >
> > I use gcc on PC.
> > Thanks
> >
> >    
>
>
>