There is no need for SIGNAL=Y as far as MainView and RTCS are concerned.
MAXLENGTH must be at least 39 under all circumstances. MainView Infrastructure itself and MainView products that use the so-called "Enhanced Security" interface never generate an ENTITY name longer than 39 characters, but certain MainView products, those that use the so-called "Basic Security" interface, do generate ENTITY names that are longer than 39 characters. In that case, you should specify 61. But when asked for a suggestion, we usually respond with "64". But there is no reason to not to make it 92, or 127, or 253. The only component that cares (and enforces) this maximum length limitation is RACF itself, and BMC Software will likely never, ever generate any ENTITY name longer than 61 characters. So, as long as it is at least 61, you can safely set the MAXLENGTH value to anything you wish: 61, 64, 142, 250, 253, whatever.