In the 'Allocate New Data Set' screenshot, it says - for the expiration date field - that the formats are 'YY/MM/DD, YYYY/MM/DD, YY.DDD, YYYY.DDD in Julian form, DDDD for retention periods in days or blank'. (I added some commas, which I assume are supposed to be there, but are just line breaks in the screenshot.)
Does that mean z/OS supports the Julian calendar?