'\"macro stdmacro
.if n .pH g5.ucontext @(#)ucontext	40.9 of 10/27/89
.\" Copyright 1989 AT&T
.nr X
.if \nX=0 .ds x} ucontext 5 "" "\&"
.if \nX=1 .ds x} ucontext 5 ""
.if \nX=2 .ds x} ucontext 5 "" "\&"
.if \nX=3 .ds x} ucontext "" "" "\&"
.TH \*(x}
.SH NAME
\f4ucontext\f1 \- user context
.SH SYNOPSIS
\f4#include <ucontext.h>\f1
.SH DESCRIPTION
The 
\f4ucontext\fP
structure defines the context of a thread of control within an 
executing process. 
.PP
This structure includes at least the following members:
.PP
.RS
.ft 4
.nf
ucontext_t  uc_link
sigset_t    uc_sigmask
stack_t     uc_stack
mcontext_t  uc_mcontext
.fi
.ft 1
.RE
.PP
\f4uc_link\fP
is a pointer to the context that to be resumed when this context returns.
If
\f4uc_link\fP
is equal to 0, then this context is the main context, and the process
exits when this context returns.
.PP
\f4uc_sigmask\fP
defines the set of signals that are blocked when this context is active [see
\f4sigprocmask\fP(2)].
.PP
\f4uc_stack\fP
defines the stack used by this context [see
\f4sigaltstack\fP(2)].
.PP
\f4uc_mcontext\fP
contains the saved set of machine registers and any implementation specific
context data.
Portable applications should not modify or access 
\f4uc_mcontext\fP.
.SH SEE ALSO
\f4getcontext\fP(2), \f4sigaction\fP(2), \f4sigprocmask\fP(2),
\f4sigaltstack\fP(2), 
\f4makecontext\fP(3C).

