ucontext(5)                                                     ucontext(5)


   NAME
         ucontext - user context

   SYNOPSIS
         #include <ucontext.h>

   DESCRIPTION
         The ucontext structure defines the context of a thread of control
         within an executing process.

         This structure includes at least the following members:

               ucontext_t  uc_link
               sigset_t    uc_sigmask
               stack_t     uc_stack
               mcontext_t  uc_mcontext

         uc_link is a pointer to the context that to be resumed when this
         context returns.  If uc_link is equal to 0, then this context is the
         main context, and the process exits when this context returns.

         uc_sigmask defines the set of signals that are blocked when this
         context is active [see sigprocmask(2)].

         uc_stack defines the stack used by this context [see sigaltstack(2)].

         uc_mcontext contains the saved set of machine registers and any
         implementation specific context data.  Portable applications should
         not modify or access uc_mcontext.

   SEE ALSO
         getcontext(2), sigaction(2), sigprocmask(2), sigaltstack(2),
         makecontext(3C).




















   7/91                                                                 Page 1