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

  Sets the current signal mask.

  Syntax:

        #include <signal.h>

        int sigprocmask (int how, const sigset_t *set, sigset_t
       *o_set);