Using either C or Python
If you do not know what the stack is here is a lightweight introduction
Every time you call a subroutine, it creates a stack frame. This is the holding area for variables and other information local to the subroutine. In this case, when you call ping() it creates a stack frame that holds information for the subroutine call. Simplistically, the frame says that says ping pinged. When it calls pong(), this creates another stack frame that says pong ponged. The stack frames are chained together, with each subroutine call acting as a link in the chain. In this case, the stack basically says ping pinged so pong ponged. Of course when pong() calls ping() this extends the stack.
Here is a visual representation:
1 ping pinged
2 ping pinged so pong ponged
3 ping pinged so pong ponged so ping pinged
4 ping pinged so pong ponged so ping pinged so pong ponged
A stackless Apache would allow for systems with very little memory to run the Apache serverNow imagine that the page width represents the memory that your system has allocated to the stack. When you hit the edge of the page, you overflow and the system runs out of memory. Hence the term stack overflow
So when a user requests a page apache wouldn't have to spawn process after process
Thus reducing DoS also
Anyway just throwing my ideas around will have to figure out a way to implement it now