internal _IOCompletionCallback(IOCompletionCallback ioCompletionCallback, ref StackCrawlMark stackMark) { _ioCompletionCallback = ioCompletionCallback; // clone the exection context _executionContext = ExecutionContext.Capture(ref stackMark); ExecutionContext.ClearSyncContext(_executionContext); } // Context callback: same sig for SendOrPostCallback and ContextCallback