If you create an SMS managed data set with an expiration date. The expiration date showed up in the VTOC and in the catalog entry.
Then delete the data set and reallocate it on a non-SMS managed volume. The expiration date will show up in the VTOC, but not in the catalog entry.
At my shop, I then repeated the test. I was able to update both the catalog entry and the VTOC for the SMS managed data set. I was able to update the catalog entry, but not the VTOC, for the non-SMS managed data set.
Note: You cannot use the EXPDT parameter to change the expiration date of an existing SMS data set.