If a core file is not left after a LISTSERV crash then it is most likely that you need to change some system-wide setting to allow the operating system to write a core file. (See the man page for 'ulimit'.)  For instance some unixes have a maxcorefilesize setting (or equivalent -- check the documentation for your particular unix) that defaults to a value that is too small to handle a LISTSERV core dump, which can be quite large. The bottom line is that if a core file is not written after a crash, it's not being written due to an operating system constraint, not because of something LISTSERV is or isn't doing.