Kenneth E. Codlin will resign as chief investment officer of the $9 billion State Universities Retirement System of Illinois, Champaign, effective Nov. 26, upon his qualification for disability. The board issued RFPs last week for an executive recruiting firm to conduct a nationwide search for his replacement, said James M. Hacking, executive director. It hopes to select a search firm by the end of November. John R. Krimmel, associate investment officer, will be appointed acting CIO, effective with Mr. Codlins resignation. The board asked Mr. Krimmel to be a candidate for the permanent position. Mr. Hacking expects the search to begin in December and take about four months. He said the board could make a decision in the spring. Mr. Codlin, who joined SURS as CIO in 1987, may continue to work part-time for the system after he goes on disability, depending on his health and the needs of SURS.