Atlanta's mainstream jazz showcase, e.j.'s, will be busy for the next month or so. The Buckhead restaurant/music room sold out a one night stand by the Dexter Gordon Quartet on May 4 and guitarist Chuck Wayne, who records for Progressive Records (based in Tifton, GA), was in residence through May 10. Guitarist Cal Collins, a Concord recording artist, will be at e.j.'s from May 27 through May 31 followed by Milt Jackson from June 3 through 6 and Mose Allison from June 10 through 14. Seems like Steve Negri waits for things to warm up outside before things really start cooking inside his coolest of hangouts.

The weekend of May 16 and 17 will be a field day for jazz lovers. Violinist Leroy Jenkins, recognized the world over as the most significant artist on his instrument in the modern era, will perform a solo concert at the Academy of Medicine (7th and West Peachtree Streets) at 8 p.m. on Saturday, May 16. A Member of Chicago's visionary Association for the Advancement of Creative Musicians (A.A.C.M.), which also claims the Art Ensemble of Chicago, Leo Smith and Anthony Braxton as members, Jenkins is in the forefront of today's "New Music" establishment. General admission tickets are $3 and available at the door beginning at 7 p.m. on May 16. Call 658-6691 for more details.

Then, on Sunday, May 17, the Arts Festival of Atlanta will present the fifth annual installment of Jazz Day in Piedmont Park. Beginning at 12:30 p.m. the three stages will resound with a variety of jazz styles culminating with an appearance by tenor saxophonist Frank Foster. Foster, who spent 11 years performing, composing and arranging with the Count Basie Orchestra, is one of the greatest living jazz artists and a fierce supporter of mainstream jazz and bebop. His quartet features bassist Earl May, pianist Mickey Tucker and drummer Billy Hart, three established musicians in their own right. This performance is free to the public and was made possible by a grant from the National Endowment for the Arts.

A number of big bands will be featured during the course of Jazz Day including the winner of the college division of the big band competition being sponsored by the music department of Georgia State University on Saturday, May 16. Stephanie Pettis and Atlanta and the Steve Dwiggins Trio are two of the smaller local combos that will perform on the Jazz Day stages. Bring a blanket and a picnic!

Landslide Records, which released the debut solo recording by the native Atlantan Dan Wall and the latest from Bruce Hampton earlier this year, has two new jazz albums about to be released. Route Two, featuring Wall, percussionist David Earle Johnson and guitarist John Abercrombie, and Navigator, Paul McCandless' second solo recording, are due out this month.

Finally, Life Force, Atlanta's most durable jazz band, has released its first album, an independently produced recording entitled Fearless Warriors. A potpourri of contemporary jazz styles with one mainstream number squeezed in, the album is worth buying and is available at local record outlets.