/sys$common/syshlp/helplib.hlb CC, Run-time functions, longjmp  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Provides a way to transfer control from a nested series of function
  invocations back to a predefined point without returning normally;
  that is, by not using a series of return statements.  The longjmp
  function restores the context of the environment buffer.

  Syntax:

       #include <setjmp.h>

       void longjmp(jmp_buf env, int val);