In C++, stack unwinding is only guaranteed to occur if the exception is caught somewhere. This is because "If no matching handler is found in a program, the function terminate() is called; whether or not the stack is unwound before this call to terminate() is implementation-defined (15.5.1)." (C++03 standard, §15.3/9).[14] This behavior is usually acceptable, since the operating system releases remaining resources like memory, files, sockets, etc. at program termination.[citation needed]