The function
tracing-enabled-p
determines whether tracing (by the Common Lisp macro trace) is currently on. This is independent of whether any functions are currently traced.
The function
(setf tracing-enabled-p)
switches tracing on or off according to the value of
enabledp
. This does not affect the list of functions that are currently traced.
LispWorks User Guide and Reference Manual - 21 Dec 2011