COBOL 5.x takes a lot of memory. You may need to increase your TSO region size greater than 6000K for foreground compiles. Larger programs will need to be installed in the background with JCL changes. See Knowledge Document TEC1577921 and TEC1273827 for more info on using CA Gen with COBOL 5.x. CA Gen has not certified COBOL 6.x with any version of Gen at this time.