ABC and CBS both have formidable lineups of first-run theatrical movies for telecast this season, while NBC's inventory leans more toward the pitiful.

ABC bought such box-office behemoths as "The Sting," "The Bad News Bears," "Shampoo" (which will require quite a rinse before it can be shown), "The Pink Panther Strikes Again," "Harry and Tonto" and "Taxi Driver."

CBS has acquired the first network TV rights to "Rocky," "Marathon Man," "Network," and "Bound for Glory." It also spirited "Gone with the Wind" away from NBC for at least the next 20 years, and bought "The Poseidon Adventure" after two runs on ABC.

NBC not only has two lousy pictures on the agenda, but it is taking steps to make them conceivably worse. So that each film can be stretched out over two nights' airing, 51 additional minutes have been added to the theatrical version of the dreary Dino de Laurentiis remake of "King Kong" and another 70 minutes have been appended to the dippy adventures of a sunken 747, "Airport '77."

Other big bow-wows to show up on NBC include "The Cassandra Crossing," "The Missouri Breaks," and "Audrey Rose." But the network has also acquired rights to "The Sound of Music" for nothing less than the next two decades.

When will the big films be on? Except for early season showings, networks keep these dates hush-hush, but viewers can rest assured the most attractive titles will surface during key ratings "sweep" periods - October-November and April-May.