document core and stack
diff --git a/man/man1/core.1 b/man/man1/core.1
index b0a5b16..51d235f 100644
--- a/man/man1/core.1
+++ b/man/man1/core.1
@@ -4,9 +4,6 @@
 .SH SYNOPSIS
 .B core
 [
-.B -s
-]
-[
 .I dir
 |
 .I corefile
@@ -27,11 +24,18 @@
 .PP
 For each core file read,
 .I core
-prints the date and time the core was generated,
-the command that generated it, and, if the
-.B -s
-option is given, a short stack trace
-at the time of the core dump.
+prints the command
+.B stack
+.IR file ,
+the date and time the core was generated,
+and
+the command that generated it.
+The
+.B stack
+command, if run, prints a stack trace of the 
+executing thread at the time of the core dump;
+see
+.IR db (1).
 .PP
 If no arguments are given,
 .I core
@@ -49,7 +53,3 @@
 .IR acid (1),
 .IR db (1),
 .IR core (5)
-.SH BUGS
-The
-.B -s
-option is not implemented.
diff --git a/man/man1/db.1 b/man/man1/db.1
index 38c8fc1..5d0945d 100644
--- a/man/man1/db.1
+++ b/man/man1/db.1
@@ -14,6 +14,16 @@
 |
 .I corefile
 ]
+.PP
+.B stack
+[
+.I textfile
+]
+[
+.I pid
+|
+.I corefile
+]
 .SH DESCRIPTION
 .I Db
 is a general purpose debugging program.
@@ -78,6 +88,13 @@
 otherwise the map is undefined and accesses to it
 are not permitted.
 .PP
+.I Stack
+takes the same arguments as
+.IR db .
+It prints a stack trace (see the
+.B $c
+command below) and then exits.
+.PP
 Commands to
 .I db
 are read from the standard input and
@@ -939,7 +956,8 @@
 Beware that local variables may be stored in registers; see the
 BUGS section.
 .SH "SEE ALSO"
-.IR acid (1)
+.IR acid (1),
+.IR core (1)
 .SH SOURCE
 .B \*9/src/cmd/db
 .SH DIAGNOSTICS