AUSTIN, TEX. ? A retired Texas oilman has pledged his estate  worth an estimated $150 million  to the University of Texas, which school officials said was the largest gift ever made to a single public university.

The donation by John “Jack” Jackson, who graduated from UT in 1940, is a testament to the role the school played in his life, university president Larry Faulkner said in announcing the gift on Saturday.

Jackson, 88, was unable to attend the announcement because he was ill at his home in Dallas, Faulkner said.

“He has great belief in the very positive effects that this university brought to his life,” Faulkner said.

Larger gifts have been made to private schools, UT officials said, including the $600 million that Gordon Moore, co-founder of computer chipmaker Intel Corp., is donating over 10 years to the California Institute of Technology. That gift was announced in October as the largest ever made to a single American school.

In 2000, Jackson and his late wife, Katie, donated $15 million for the expansion of the school’s Geological Sciences Building. Last July, they gave a $25 million endowment to create the John A. and Katherine G. Jackson School of Geosciences.

Jackson specified a range of items the money can be used for, including scholarships, research and faculty support, Faulkner said.