Available Stack Memory

I present here an undocumented method for approximately (i.e, playing on the safe side) determining how much stack memory is available.

Undocumented, means it should not be used for production software even when, as is the case, it has been consistent for all Windows releases since NT.

Here is the 32-bit version, the 64-bit is in the downloadable .ZIP.

.386

; Compile with
; uasm64 -c -coff deallocationStack32.asm
; or
; ml /c /coff deallocationStack32.asm

.MODEL FLAT, C
option casemap:none 

RESERVED_SPACE equ 4096 * 16 ; safe-side estimate

.code

availableStackSpace proc public
	lea eax, [esp] 
	assume fs:nothing
	mov edx, fs:[0e0ch] ; DeallocationStack in TEB
	assume  fs:error
	sub eax, edx
	sub eax, RESERVED_SPACE
	ret
availableStackSpace endp

end

Download Source Code with C++ project (2017)