The American Security Corp.'s annual meeting was the briefest in memory, said some of the small group of shareholders who gathered yesterday in a room at the top of the company's headquarters here, across Pennsylvania Avenue from the Treasury Department.

In just over 20 minutes, the chairman and president addressed the gathering, some parliamentary procedures were taken care of routinely and a single stockholder responded to the offer by management to answer questions.

Reflecting the quietly upbeat of the meeting, President W. Jarvis Moody noted: "In 1977 we achieved the largest dollar growth in earnings and assets in our history."

ASC is the holding company for American Security Bank, and together they had net income last year of $17.6 million ($7.24 a share), up 10 percent over a year earlier.

Moody also commented briefly on earnings for the first quarter of 1978, which were $4.5 million ($1.83 a share), compared with $4 million for the same period of 1977.

"This represents an increase of nearly 10 percent and was due in large part to loan volume, which was up considerably over the first quarter of 1977," Moody said.

He added that net income after securities gains was slightly ahead "because of substantial security gains in the first quarter of 1977."

The only question from the apparently satisfied shareholders was whether there is any "monetary value" to the previously 3-for-2 stock split, which was approved yesterday by the shareholders and becomes effective at the close of business April 28.

Carleton M. Stewart, chairman of the board, explained that "the split will result in a lower market price which should make the stock attractive to individual investors and provide a broader market for our stock."

The 3-for-2 split will increase the number of shares outstanding from 2.4 million to 3.6 million. ASC, which trades over-the-counter, has been selling in the $44 to $46 range, Stewart noted.

ASC has announced that, after the split, the quarterly dividend will continue at the rate of 50 cents a quarter, an amount equal to the pre-split 75 cents per share dividend established in the first quarter of 1978.