For casual times, a comfortable combo is jeans and a colorfully striped top, from Lane Bryant. Below: Printed douppoini silk ensemble includes a jacket, blouse and skirt. A M PLE 1M AG E DESIGNERS AND MANUFACTURERS ARE PAYING ATTENTION TO LARGE SIZE WOMEN. THE RESULTS ARE GLAMOROUS NEW CHOICES FOR CAREER AND EVENING DRESSBG. BY R.S. SPENCER 70 I N STYLE I arge size women. They have become the hot- test topic in the fashion j industry. According to The National Retail Merchants Association's vice president of merchandising, Joseph Siegal, 26 million women in this coun- try wear a size 16 or larger. With those numbers, many designers and manufacturers have awoken to the cries of large size women for fashionable clothes. Oleg Cassini took the plunge with the introduction of a spring line. Claire Pasterick, president of the large size division, says, "The customer is getting what she wants, which is the same styling and clothes as the missy customer. The customer is ask- ing for better merchandise, quality and style and she doesn't care about the price." Givenchy En Plus and Albert Nipon have also made inroads in this market. Helen Genute, head of public relations at Givenchy, says, "We get our design direction from Paris for color, fabric and silhouettes. Now, the large size woman is no longer two years behind her missy counterpart." This season, Givenchy shows trapeze-shaped tops with shorter, slimmer skirts, in both navy and white and in sand tones. Jacqueleine Van Cise, account executive for the large size division of Albert Nipon, in operation since 1985, agrees that nautical colors and tunic tops over slim skirts are hot this spring. "The designer name