This variable is used by the debugger when it displays the stack frames. Open frames are made by the system and are normally not shown by the debugger. However if
is set to
then the open frames are displayed. It is unlikely that you need to examine open frames: their use is connected with implementation details.
USER 52 > (setq dbg:*print-open-frames* t)
Type :c followed by a number to proceed
LispWorks User Guide and Reference Manual - 21 Dec 2011