8.3.4 The RexxDeregisterFunction() function This function is used to remove a particular external function handler from the list of registered external function handlers. The prototype of the function is: APIRET APIENTRY RexxDeregisterFunction( PSZ FuncName ) ; The parameter is an input values: [FuncName] Points to an ASCII NUL terminated character string which defines the name of the external function to be registered. This is the same name as the REXX interpreter uses with a function call or via the CALL command. The list of defined function handlers is searched, and if an environment matching the one named by the parameter are found, it is deleted. This call is used to de-register function handlers registered with either RexxRegisterFunctionExe() or RexxRegisterFunctionDll(). The returned value from RexxDeregisterFunction() can be one of: [RXFUNC_OK] The handler was successfully deleted. [RXFUNC_NOTREG] The handler was not found. Most systems that do have dynamic linking have no method for reclaiming the space used by dynamically linked routines. So, even if you were able to load a dll, there are no guarantees that you will be able to unload it.