> 4kb is a laughable amount of stack

"Laughable" is your argument that you would rather increase stack usage function by 1000% because it would make it thread-safe before even considering proper synchronization with a mutex. That for a code that is nowhere near needing thread safety .

> if stack overflows are your only argument then I will not discuss this any further

Let me get this straight: You open a PR tagged with 'RFC' but are not willing to discuss it? Next time do me a favor and save us both some time by NOT opening a PR.