The biggest thrill ride in Hollywood is the performer's breathtaking swoops and plunges on the Big Screen roller coaster.

Actors work and sweat and, if they're lucky, eventually reach some sort of pinnacle. But inevitably the law of gravity comes into play and they slide down to idleness.If they hang in long enough, they may rise and dive again in the never-ending peaks-and-valleys of the toughest job imaginable.

Occasionally, they drop out of films to settle for the relative security of the flat course offered by a TV series. If the series is a hit they settle for the same role every day for five years. By that time the movie roller coaster has left them at the gate.

Alan Arkin, one of the screen's most talented non-stars, is riding the crest once more with three movies to his credit this year - and more to come.

Currently, Arkin is starring in "The Rocketeer," the biggest film Disney has ever made. It will be released next summer. He also will be seen in "Havana" with Robert Redford and "Edward Scissorhands" with Johnny Depp, both to be released on the same weekend this month.

Arkin, unsmiling, said, "This is the busiest year I've ever had in the business."

Although he has given brilliant performances in "The Russians Are Coming, The Russians Are Coming," "The Heart is a Lonely Hunter," both of which earned him Oscar nominations, "Popi," "The In-Laws" and "Catch 22," he has never attained superstardom.

Perhaps he never will. But the dark-visaged, astute Arkin is not concerned. He refuses to rely on motion picture acting as his only creative activity or sole source of income.

"Every actor depends on other people for work," he said. "Agents, managers, casting directors and producers. But too many actors sit at home between roles and wait for the telephone to ring. That's death.

"A lot of people think waiting for that important call is doing something. It's nothing. They believe some kind of magic will happen if they concentrate hard enough on hearing from their agents.

"I don't look at the telephone and I've only had about three weeks off from movies this year. Don't ask me why I've been so much in demand.

"Actually, I did sign with a new agent - Diane Kamp - about 16 months ago, which may account for this amazing resurgence of interest in me. I hold her responsible for the energy that's come into my career.

"Another thing, I've turned down a lot of parts in recent years. I don't want to spend the rest of my life playing the dentist character I did in 'The In-Laws.'

"I like to play a variety of different parts. As a result of that I think people don't know who I am or what I do. Even when I get a role, I'm usually the fourth choice for the part.

"That's because I'm not typed, so I'm not the first actor to come to mind for a specific kind of character.

"My agent comes in after the producers have exhausted the first three possibilities for a role. She says, `What about Alan Arkin?' They say, `Hey, that's an interesting idea. Maybe he could do it."'

Arkin says he's not an aspirin bottle with a recognizable label, which means he is often overlooked.

"It hasn't been very good for business, but it's made for a lot more fun," he said.

"I've managed to siphon off my insecurities. I'm so insecure I can't stand to sit around biting my nails, so I started in doing other things. Since then, I'm a lot more relaxed. A lot happier."

In the past 20 years Arkin has directed some 20 successful plays on and off Broadway and several TV movies, including "Trying Times" for PBS, which won six Emmy Awards.

Dry movie spells don't bother him now.

"Like all of life, there are ebbs and flows and cycles," he said. "At the moment I'm grateful that I seem to be in demand. That could change next year or next week.

"I've written four published books, a couple of them children's books. And some of the best acting things I've done were for mini-series and TV.

"Acting is a creative discipline. If an actor can't express his creativity on stage or camera, it has to surface somewhere. Often it's writing or painting or music.

"An actor needs an audience. The other arts can be practiced by a solitary individual. Given my choice, however, I would like to stick pretty much to acting. It's what I do."