Fluffy, frothy 'Razzle'; '42nd Street' dazzles; Within' needs elbowroom; 'Nightclub Cantata' merely survives; 'Within' in a big space

Maybe it's because the 32 artists renting studios at the Boston Center for the Arts work cheek by jowl in close quarters. Or because the BCA's South End neighborhood is a place of tiny streets. Whatever the reason, the abiding impression of their third annual exhibition, ''Within 1984'' (at the Cyclorama, through June 17), is one of smallness.

Granted, the cavernous Cyclorama would dwarf a locomotive: Even the 30 -foot-high fabric construction (''Outer-Inspace''), by Michael Roy Layne and his students, seems somehow modest. Kyle Hanton's elegant, ethereal pieces help: Built of thin pine struts covered with pastel nylon fabric, they hover kitelike overhead and help lower the ceiling.

Still, most of the 100 pieces in this show (chosen from the 32 BCA artists by David Ross, director of the Institute of Contemporary Art) are small - in size, scope, and conception. Some exceptions: Harel Kedem's ''Josef'' (playing deftly on the biblical patriarch's coat of many colors); Richard Harden's solid ''Crucible'' (depicting a steelworks) and ''Poland Suite'' (four lithographs of blue-collar Poland); and Alan Keith's ''Still Life,'' which generates a pale radiance from within. But too much here is merely derivative. These artists, some with obvious talent, need a breaking out: They need the elbowroom to escape Boston's taut intellectuality and trust their intuition.