NEW YORK (AP) _ Friends and Catholic Relief Services co-workers of the Rev. Lawrence Jenco gave thanks for answered prayers Monday with a Mass of Celebration for his release after 19 months as a hostage in Lebanon.

''Let this be another lesson on how powerful prayers can be,'' the principal celebrant, Archbishop Theodore McCarrick of Newark, N.J., told the group of about 200 people.

The service was held at the Church of St. John the Evangelist, in the same building as the world headquarters of CRS, which had been saying Mass for Jenco's release twice a week since his capture.

''For so many months we have been working and praying. This is no longer a ransom petition, but a Mass of thanksgiving. We come here to thank the Lord for listening to our prayers,'' said McCarrick, who chairs the CRS Board of Directors Sub-Committee on Eurasia.

Jenco, who was director of CRS in Lebanon when he was taken hostage on Jan. 8, 1985, was released Saturday. On Monday, he was in Weisbaden, West Germany, where he was reunited with his family.

McCarrick thanked church and government agencies that worked toward Jenco's release but added that the hostages still being held in Lebanon could not be forgotten.

''There are still those in captivity. We cannot stop praying. We still have others over there,'' he said, referring to hostages Terry Anderson, chief Middle East correspondent for The Associated Press; David Jacobsen, director of the American University Hospital in Beirut; and Thomas Sutherland, the university's acting dean of agriculture.

One of seven other celebrants, Monsignor Robert Charlebois, director of Eurasia CRS, said CRS staff members have ''been on a high'' since Jenco's release.

Vowing to continue CRS work in Lebanon, McCarrick said, ''Catholic Relief Sevices is as committed now as it always has been. We must be committed to the gospel, church and to the poor.'' He said Jenco exemplified ''what this agency is and would be.''

Lawrence Pezzullo, executive director of CRS, said the agency would like continue Masses in the hope that the other hostages will be released.

Catholic Relief Services is the overseas relief and development agency of the American Roman Catholic community, working in more than 60 countries.

CRS spokeswoman Beth Griffin said Jenco is supposed to meet with Pope John Paul II in Rome sometime this week.

Elsewhere, the wife of another pastor who also had been held hostage said her husband ''must be absolutely delighted'' at Jenco's release.

''They were very close,'' Carol Weir said of her husband, the Rev. Benjamin Weir, who was traveling Monday. Weir, a Presbyterian minister, was released Sept. 9, 1985.

''I know the Father Jenco led the captives in Mass several times. They had communion services,'' Mrs. Weir said. ''I know he (Weir) must be very delighted. Of course.''