By default, the call frame for each active function call in the backtrace is listed in the Backtrace area. There are a number of other types of call frame which are hidden by default. Display call frames of these types by selecting them in the View Frame panel of the debugger Preferences:
Displays all the binding frames in the Backtrace list.
Lists the catch frames in the Backtrace list.
Lists the handler frames in the Backtrace list.
Lists any hidden symbols in the Backtrace list.
Lists all the restart frames in the Backtrace list. Each restart frame is listed, with the restart action to be taken given in brackets. To restart execution at any restart frame, select the frame, and choose Debug > Frame > Restart Frame .
Lists all invisible frames (such as the call to the error function itself) in the Backtrace list.
Note that all these commands can be toggled: choosing any command switches the display option on or off, depending on its current state. By default, all the options are off when the debugger is first invoked.
LispWorks IDE User Guide (Macintosh version) - 25 Nov 2011