Two Maryland firms--Maryland National Corp., the Baltimore-based bank holding company, and STSC Inc., the Rockville-based management services company--have named new chief executive officers.

Maryland National President Alan P. Hoblitzell Jr. was elected chief executive officer at Maryland National's annual stockholders meeting last Friday. William M. Gibson has been appointed president and chief executive officer of STSC Inc., effective May 31.

Maryland National's board of directors reelected Robert D.H. Harvey as chairman of the board of Maryland National Corp. and Maryland National Bank. Hoblitzell also was reelected president. Harvey has served as chief executive officer of the holding company since 1964.

"I have been Maryland National's chief executive officer for 19 years," said Harvey. "With only two years before a scheduled retirement, it is now appropriate to pass additional responsibility to Alan Hoblitzell."

Hoblitzell was elected president of Maryland National Corp. and Maryland National Bank in 1976 and has served as the bank's chief executive officer for four years.

Maryland National Corp. is a registered bank holding company whose principal asset is the capital stock of Maryland National Bank. The bank has 195 Maryland branch offices, loan production offices in Washington and Virginia, and several branch and representative offices overseas.

William M. Gibson succeeds STSC's founder, Daniel Dyer, who resigned. Dyer will be a consultant to STSC after his resignation becomes effective May 31.

Gibson joined STSC in September 1982 as chief operating officer. He was formerly vice president of marketing with Strategic Information, a subsidiary of Ziff-Davis Publishing Co. in Burlington, Mass. Gibson also worked in sales and marketing management positions at Chase Econometrics/Interactive Data Corp. in Waltham, Mass., for more than seven years. His 16-year experience in the data processing industry also includes positions with IBM Corp., Applied Logic Corp. and ITT Data Services.

STSC is a firm that designs computer information systems for corporate financial management and other fields. It was founded in 1969 and went public in 1978 before being acquired by Continental Telecom Inc. (Contel) of Atlanta. Revenues from 1982 operations totaled $25 million.

STSC has branch offices in 15 U.S. cities, operates subsidiary companies in Paris and London and licenses software through distributors outside the United States.