deadlock can occur. By calling ASYNC_block_pause() immediately after acquiring the lock and ASYNC_unblock_pause() immediately before releasing it then this situation cannot occur.</p>

<p>Some platforms cannot support async operations. The ASYNC_is_capable() function can be used to detect whether the current platform is async capable or not.</p>

<p>Custom memory allocation functions are supported for the POSIX platform. Custom memory allocation functions allow alternative methods of allocating stack memory