Montgomery County Executive James P. Gleason yesterday proposed a half-billion dollar 1978 operating budget which includes for a 4 per cent cost-of-living increase for county employees and no increase in the general property tax.

Briefing reporters during a morning news conference, Gleason also sharply criticized the county school board, whose budget request he cut by $10 million, and announced he had submitted two measures to the Maryland General Assembly that would radically change how the School Board operates.

Specifically, Gleason allocated $252.4 million of his proposed $509.4 million for school system costs. Last year the schools received $242 million of the county's $474 million budget.

Gleason said that although it would entail some cuts in school staff and programs, the amount was "adequate" to maintain a quality program.

"There's been a kind of slogan in this county that the more your spend on education, the better the quality of education," Gleason told a small audience that for a time included an elementary school class touring the County Office Building. "That assumption needs to be challenged."

Despite Gleason's assurances, County Council members said the property tax rate may have to be increased to finance the budget. The current average tax rate is $3.91 per $100 of assessed value. Property is assessed annually at 50 per cent of market value.

"The Council's made no flat statement against a property tax increase," council president John Menke said. "We just don't know now what will happen."

Gleason's proposed 4 per cent cost-of-living increase for all county employees, which would cost $11 million to fund, 4 per cent raise includes the school teachers who recently negotiated a 6 per cent salary increase agreement with the school board.

The council, however, can set aside that agreement by not providing enough money.

Although the proposal cuts $22.4 million from budget requests of all county agencies, it does provide for a $3 million increase in the county's mass transit fund.

The money would be used to fund the county's expanded "ride-on" minibus service in the lower portions of the county, particularly the Silver Spring area where a Metro staiton will open in November.

The expanded service will provide 120 jobs, county officials said. Gleason's budget would abolish 175 of 200 vacant county positions that were frozen several months ago. As a result, the budget would provide a net decrease of about 40 jobs, county officials said.

In general, the budget reflects Gleason's stated concern over slowed growth of county revenues, rising costs of county expenditures and the "heavy impact" government spending, particularly on less affluent taxpayers.

Gleason said that while government revenues will increase by 6.3 per cent by 7.3 per cent.

The most significant increase in expenditures, county officials said, is for fixed costs such as social security and retirement fund payments, hospitalization insurance and utility costs. Of the $20.9 million increase in the budget for just the county government, all but $400,000 is due to increased costs for these items.

Gleason's sharp words directed at school officials reflected his irritation at the school board's ignoring a warning from both him and the County Council that the school budget request had to be around $250 million.

County Council members, while expressing concern over how the county will fund the school budget request, generally disagreed with Gleason's efforts to win powers from the legislature that would give him greater control over school board affairs. Both the school board's budget request and Gleason's bid for more power were viewed as "steps backward" for the school system in general.

One measure Gleason has submitted to the legislature would transfer authority to appoint the school superintendent and to determine how school funds are spent from the school board to the county executive. The other measure would force the school board to seek voter approval for property taxes needed to support school programs.

Gleason, who repeatedly has accused the school board of ignoring the county government's serious revenue problems, said either measure is acceptable to him.

He acknowledged he felt the chances of either passing the legislature are slim, but said, "it's time to start the public discussion" about the board's fiscal accountability.

The all-Democratic Council, which will hold six public hearings on the budget, can make changes in specific items of the budgets as proposed by Gleason, a Republican. It cannot, however, insert new items.

Four of the budget public hearings will be held at county high schools and two in the Council's chambers during the last week of March and first week of April. The budget must be voted upon by May 15, county officials said.