It is a strange location for a Marine combat platoon, but there are some advantages -- like gifts of pound cake from the neighbors.

One platoon of the 32nd Marine Amphibious Unit helping to secure Beirut port to safeguard the departure of Palestine Liberation Organization guerrillas from this war-battered Lebanese capital is bivouacked in a bombed-out warehouse.

Right next door, civilian life is continuing without a break in a shell-pocked, three-story apartment building. Laundry flutters from a clothesline, and there is constant Arabic chatter by women and children. They seem oblivious to the fact that the Marines have a fortified machine-gun emplacement on top of the building.

Last night, just hours after the Marines set up camp for a month, a woman baked a cake and her husband gave it to their new temporary neighbors, providing a break from their diet of C-rations.

Marine officers say that two days into their new assignment, shared with Italian and French troops, of providing security for the Israeli-forced PLO withdrawal from Beirut, the operation at the port is going smoothly.

The role of the 800 Marines is limited to the walled-in port area, which is outside the mainstream of life in Beirut since there is little shipping activity in the harbor except for the vessels transporting the PLO fighters.

The Marines are equipped with their personal weapons, either M16 rifles or pistols, mortars, machine guns and antitank missiles. Aboard the five task force ships they have artillery, tanks and helicopters in case they are necessary. They are under order to defend themselves if fired upon.

Despite firing in the air by departing guerrillas, the atmosphere in the port area is calm.

One leatherneck pointed out that unlike yesterday, he did not have his grenade launcher armed today. While not all Marines have their weapons loaded, all carry ammunition with them and can load their weapons quickly.

The entrance to the port is guarded by Marines and Lebanese Army soldiers. Fluttering from the gate are large pictures of Lebanese President-elect Bashir Gemayel, wearing a business suit rather than the camouflage uniform of his Lebanese Forces militia featured in earlier pictures.

Fifty yards away, three Israeli soldiers sit in front on their American-built armored personnel carrier.

Their mission, they say, is to stop any Israeli military vehicle from entering the area since it is a "diplomatic zone" designed to provide protection for the PLO evacuation.

The Italian soldiers, who disembarked today, and the troops of the French Foreign Legion, who started the 2,000-man multinational operation Saturday, are located in more sensitive positions at the crossing points between East and West Beirut and along the highway to Damascus to protect overland departures.

That is perhaps due to the sensitivity of the American position in the Middle East, where many Arabs regard the United States as being partial to Israel.

Most Marines have discounted what is apparently the biggest danger so far in the mission -- the constant firing straight up of automatic weapons by the departing PLO troops who spray the air to demonstrate that they are still a military force and to put a victorious image on their withdrawal.

Sometimes the spent bullets land fewer than 10 yards from the Marine positions at the port, but they are not regarded as a hazard, as the troops all wear helmets and flak jackets.

"It doesn't bother any of us as long it goes straight up and nobody is pointing weapons at us," said Staff Sgt. William Goode Jr.

"It's like the Fourth of July every day," an officer said, noting that many of the men watched last night as the firing lit up the Beirut skyline.

Lt. Col. Robert Johnston called the firing "asinine" by standards of the safety-conscious U.S. military, but added that there were "cultural differences" that should be taken into account. He also noted that the firing was decreasing each day.

Johnston also played down meetings he held yesterday and today with Col. Saleh Abu Zared of the Palestine Liberation Army, calling the brief sessions "technical" and "logistical" to complete arrangements for the Palestinians to board ships.

The meetings, he said were all held in the presence of Lebanese Army officials, but since the Marines are in charge, "there is clearly a requirement to coordinate with the PLO."

The United States refuses to deal diplomatically with the PLO, and he said the Marines' orders were to keep contact to a minimum.

The troops are not receiving combat pay because they are not at war.

Most were happy to be off their assault ships and on land even if they are not destined to get out of the port area during the scheduled one-month stint.

"There will be no liberty in West Beirut," said Capt. Richard Zilmer of Reading, Pa. "This is as good as it gets."