'\" te
.\" Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved.
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.TH getustack 2 "2 Nov 2004" "SunOS 5.11" "System Calls"
.SH NAME
getustack, setustack \- retrieve or change the address of per-LWP stack
boundary information
.SH SYNOPSIS
.LP
.nf
#include <ucontext.h>

\fBint\fR \fBgetustack\fR(\fBstack_t **\fR\fIspp\fR);
.fi

.LP
.nf
\fBint\fR \fBsetustack\fR(\fBstack_t *\fR\fIsp\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBgetustack()\fR function retrieves the address of per-LWP stack boundary
information.  The address is stored at the location pointed to by \fIspp\fR. If
this address has not been defined using a previous call to \fBsetustack()\fR,
\fINULL\fR is stored at the location pointed to by \fIspp\fR.
.sp
.LP
The \fBsetustack()\fR function changes the address of the current thread's
stack boundary information to the value of \fIsp\fR.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, these functions return 0. Otherwise, \(mi1 is
returned and \fBerrno\fR is set to indicate the error.
.SH ERRORS
.sp
.LP
These functions will fail if:
.sp
.ne 2
.mk
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 10n
.rt  
The \fIspp\fR or \fIsp\fR argument does not refer to a valid address.
.RE

.SH USAGE
.sp
.LP
Only implementors of custom threading libraries should use these functions to
get and set the address of the stack bound to an internal per-thread data
structure. Other users should use \fBstack_getbounds\fR(3C) and
\fBstack_setbounds\fR(3C).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(5.5i) |cw(0i) 
lw(5.5i) |lw(0i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityEvolving
_
MT-LevelAsync-Signal-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fB_stack_grow\fR(3C), \fBstack_getbounds\fR(3C), \fBstack_inbounds\fR(3C),
\fBstack_setbounds\fR(3C), \fBstack_violation\fR(3C), \fBattributes\fR(5)