__STACK_SIZE has no effect

[silvio3105]

Hi,

I defined __STACK_SIZE as compile/build flag. It has no effect according to GCC output after building is done.

Chip is nRF52840.

I tried to set fixed stack size in startup file and it did not changed RAM used size. Both linker script and startup file are from nRF5 SDK v17.1.0

What I'm doing wrong? 

[Turbo J]

You are using an outdated and unsupported SDK.

Stack size won't be reflected in RAM usage IIRC - the linker has no idea about dynamic stuff.

I believe the old liker scrips initialize the SP at or near top-of-RAM anyway. The linker will start barking at you when your static stuff gets too big and reaches into the areas reserved for stack.

[silvio3105]

I know it's outdated but this is base function.
Stack must be placed somewhere. It cannot go to the FLASH region, only in RAM section.

[Hung Bui]

Hi Silvio, 
I don't think the stack size will be reflected there. But if you try to increase the __STACK_SIZE over the size of the available RAM you should be able to see the linker complaining. 
The stack is located at the high top of the RAM and expanding down from there. 
I would suggest to take a look at this ticket: 
RE: Maximum limit of stack size using flag -D__STACK_SIZE NRF52382
And this ticket
nRF52840 RAM questions regarding stack and heap