Default value: (> 5 *delivery-level*)
If this is non-nil, by default delivery retains the full TTY debugger, so it can be used when debugging delivered applications.
On Unix, if the value is :all, all debug information is kept
On all platforms, if :keep-debug-mode is set to :keep-packages, all packages are retained as well as the debugger, so that they can be used for debugging purposes.
The value of :keep-debug-mode affects the default value of the following keywords to:
:compact
:keep-clos-object-printing
:keep-eval
:keep-function-name
:keep-lisp-reader
:keep-load-function
:keep-structure-info
:keep-top-level
:make-instance-keyword-check
:no-symbol-function-usage
:packages-to-keep-symbol-names
LispWorks Delivery User Guide - 15 Feb 2015