In 1951 he earned his bachelor's degree in Architecture and a commission as 2nd lieutenant through the Air Force ROTC program.

Llenza was named Adjutant General of the Puerto Rico National Guard by Governor Carlos Romero Barceló, a position which he held from 1977 to 1983.

[1] His promotion to major general in the Air Force Reserve was confirmed by the United States Senate on February 8, 1979.

Llenza was a member of the Board of Directors of the United States Council for Puerto Rico Statehood.

[4] After retiring from the Air National Guard, Llenza worked for the United States Agency for International Development as the mission director in Quito, Ecuador, for three years.