Before a LispWorks dynamic library is unloaded, LispWorks should be made to `quit' cleanly, allowing it to clean up resources that it uses.
When the LispWorks dynamic library is loaded by a main process which you (the LispWorks programmer) do not control, then use dll-quit. If you control the main process, then use QuitLispWorks instead. For the details, see the respective manual entries for dll-quit and QuitLispWorks.
LispWorks User Guide and Reference Manual - 20 Sep 2017