CBS-TV news will stay up all night. . .
All-night TV-network news is coming in September.
CBS News will be offering a daily 2 a.m.to 5 a.m. ''Overnight Network News and Information Service'' to its affiliates.
Monitor TV critic Arthur Unger says it appears that most of the nearly 200 CBS-affliate stations will air the overnight service. The program format will include a local-news insert, as well as national and international coverage from the network.