According to this: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/Multithreading/CreatingThreads/CreatingThreads.html backgroud thread stack size for background threads is 512KB. When using plain old NSThread one control this by using NSThread.stackSize property ( https://developer.apple.com/documentation/foundation/thread/1415190-stacksize ). Is it possible to indicate that asyncDetached {} task requires more stack space than system allocates to background threads by default?