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<h2 class="chapter">8 Examining the Stack</h2>

<p>When your program has stopped, the first thing you need to know is where it
stopped and how it got there.

   <p><a name="index-call-stack-396"></a>Each time your program performs a function call, information about the call
is generated. 
That information includes the location of the call in your program,
the arguments of the call,
and the local variables of the function being called. 
The information is saved in a block of data called a <dfn>stack frame</dfn>. 
The stack frames are allocated in a region of memory called the <dfn>call
stack</dfn>.

   <p>When your program stops, the <span class="sc">gdb</span> commands for examining the
stack allow you to see all of this information.

   <p><a name="index-selected-frame-397"></a>One of the stack frames is <dfn>selected</dfn> by <span class="sc">gdb</span> and many
<span class="sc">gdb</span> commands refer implicitly to the selected frame.  In
particular, whenever you ask <span class="sc">gdb</span> for the value of a variable in
your program, the value is found in the selected frame.  There are
special <span class="sc">gdb</span> commands to select whichever frame you are
interested in.  See <a href="Selection.html#Selection">Selecting a Frame</a>.

   <p>When your program stops, <span class="sc">gdb</span> automatically selects the
currently executing frame and describes it briefly, similar to the
<code>frame</code> command (see <a href="Frame-Info.html#Frame-Info">Information about a Frame</a>).

<ul class="menu">
<li><a accesskey="1" href="Frames.html#Frames">Frames</a>:                       Stack frames
<li><a accesskey="2" href="Backtrace.html#Backtrace">Backtrace</a>:                    Backtraces
<li><a accesskey="3" href="Selection.html#Selection">Selection</a>:                    Selecting a frame
<li><a accesskey="4" href="Frame-Info.html#Frame-Info">Frame Info</a>:                   Information on a frame

   </ul>

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