You will be interviewed by 2 or more managers from the IT department. Each has a set of questions they ask. Some are technical (ie - COBOL, JCL, data sets, libraries) and some are general (experience working with teams and also individually, how do you find information on something unfamiliar). You will be taken to lunch and the Head of IT may join you. Be prepared to ask some questions of your own to show you have done some research into the company and department.