At 15:18 -0700 on 02/21/2011, Paul Gilmartin wrote about Re: SYSADATA file quirk:
Simply, the check should be coded in OPEN, and any attempt to modify the attributes of a nonempty existing data set should ABEND.
IMO - Only if this is being done in an downward incompatible way. IOW: Increasing the BLKSIZE is OK. So is increasing the LRECL (but only for a V not a F dataset). The idea is if the new settings allow members stored with the old settings to still be read, then there is no real problem. Reducing either BLKSIZE or LRECL should trigger the ABEND since it would cause read problems for members who can now exceed the new maximum LRECL or BLKSIZE lengths.
