To Barbados maintenance man Berkley Jack, the four-day-old invasion of Grenada by U.S. and Caribbean forces is a straightforward case of responding to the calls of a neighbor whose life is in jeopardy.

"If you're in your house and a man is trying to kill you and there's any way I can get police to come and rescue you, I will do it," Jack said as he watched U.S. helicopters and gunships maneuver on the tarmac of Barbados' Adams International Airport.

Despite criticism from some church and labor leaders, Caribbean leaders' unprecedented request for U.S. intervention last week seems to enjoy solid support among the 150,000 people of Barbados, which was pivotal in organizing the attack and now serves as a forward supply base.

The sentiment in five other island states which sent troops to Grenada in response to a bloody coup d'etat last week could not be directly sampled. But few overt signs of deep-rooted discontent have been reported.

In Barbados the arrival of U.S. support troops and hundreds of journalists--all needing hotel rooms, taxis and meals--has brought some welcome off-season stimulation to the economy, which depends heavily on tourism.

Four days after U.S. troops staged their surprise attack, Grenada remains at the front of everyone's mind here.

Early morning bathers on a Barbados beach trade theories on how the coup began. The talk covers power outages in Grenada, U.S. versus British military prowess and just what the Soviets wanted in Grenada.

"The Russians used the Cubans as a footstool all the time," one man volunteers shortly after a C5 Galaxy transport jet passes overhead.

Radio call-in shows are dominated by invasion talk. Many of the callers are protesting a condemnation of the invasion by the Caribbean Conference of Churches, which represents the region's major denominations.

Newspapers publish special inserts on the fighting, with the tabloid Nation announcing it will issue a Saturday edition for the first time in its 10 years of publication.

Adams Airport's observation deck is crowded through the day with people watching helicopters take off, GIs maneuver enormous cargos and C5 Galaxy transports tip up their giant nose doors to discharge their loads. Barbados state radio has issued a warning against climbing fences into the airport.

Gen. Hudson Austin, who seized power in Grenada in a coup that killed at least 17 people and imposed a "shoot on sight" curfew, is seen by many people here as nothing more than a maniac holding hostages.

"I have nothing against the Americans coming in to make peace," said a woman selling horse racing coupons on a Bridgetown streetcorner.

Some people here have expressed disappointment that British forces did not go into Grenada, which is a Commonwealth country. One woman suggested that Britain would have sent troops had black-dominated Grenada had more whites.

The coup shocked many people in the island states around Grenada, which have enjoyed years of parliamentary democracy and smooth transitions of authority.

The curfew in Grenada was particularly galling to many. Barbados' Anglican bishop, Drexel Wellington Gomez, called it "the first time in the history of the Caribbean that Christian people were prevented by the point of a gun from even going to church." Gomez has supported the invasion, saying Grenada's people "were under great duress and looking for some kind of deliverance." About 65 percent of Barbados' people are Anglicans.

Gomez criticized the Caribbean Conference of Churches for its stand against the invasion. That position was adopted without consulting member churches, he said.

The church conference's general secretary, the Rev. Allan Kirton, said yesterday that Caribbean leaders did not adequately explore other means of solving the Grenada crisis. If intervention was required, he said, it should have involved only Caribbean forces.

Kirton said he feared guerrilla resistance might continue in Grenada. The invasion created a precedent for big power intervention, Kirton said, and, because some Caribbean states declined to take part, it could hamper efforts toward regional unity.

Barbados' largest trade union, the Barbados Workers Union, issued a moderately worded condemnation of the invasion.

In Jamaica, one of the six Caribbean countries with troops in Grenada, leftist labor leaders have condemned the action. "There is hypocrisy in going into a country saying that you are going to save lives and then ending up taking lives with guns and troops," said Trevor Monroe, general secretary of the Workers Party of Jamaica.

In St. Vincent's, another island state with troops in Grenada, the St. Vincent Union of Teachers condemned the move, as did the Socialist Movement for National Unity, an opposition party.