Hello everyone!

I'm interested if there is some way to allocate heap without api calls ? Like stack allocation:

Could be heap allocated something like this ? I'm don't know enough to see how API calls work inside so.. just asking Thank you.

There are two problems with using the stack for heap space.

1) Your stack size is limited at thread startup. You can't arbitrarily expand it at will later.
2) You need to touch the stack in 4kB intervals to trigger the page guard so the OS will commit memory.

As long as you understand those things then you can use the stack for heap space.

You don't understand me, I meant, how to manually do something like this API calls:

Using stack as a variables memory is common practice. But there is a one big disadvantage - you can't free and resize the memory other way than LIFO. If you defined A, B, C, D, then you can resize/free only D. If you want to resize B, then you must free D and C, resize B and allocate C and D again.
Also, these variables can be only local and they can be changed only on the same nesting level where they have been defined.
The big advantage is that there is no fragmentation in the heap.

You can't. The OS controls memory allocation. If your app needs memory it needs to ask for it in some way. Extending the stack is one way to ask for memory, any other type of memory and you must ask the OS.

I get it, thank you guys

I just want to add that 'n' cannot be a random number - it must be a number divisible by 4 (a size of a DWORD). Some Win API may fail if you call them with mis-aligned ESP.

Also, 4Kb pages remark is applied if stack is not commited.
In FASM, you can add a line at the top of source (after PE GUI 4.0 declaration):

It will reserve AND commit stack space for 1Mb, so you can allocate more than a page of room if needed.

Is there any API call to reserve more stack size ? on runtime I mean.

You can create a new thread with a new stack size, but AFAIK there is nothing that will alter the currently running thread's stack reservation.

A good question may be is: "why so much stack is needed?" - which will indicate a code design issue(s). I have built significant programs in FASM (my OOP IDE as an example) and I never needed more than 32Kb of stack and even that was a lot.

I was thinking to use stack instead of heap.. Just I'm curious, nothing else.