When upgrading to z/OS V2R4 or V2R3 both with PTF for SDSF APAR PH26541 applied, you might notice the change of behavior for JC# or JC$ commands.
According to z/OS V2R4 SDSF User's Guide (SC27-9028-40), for example, SDSF JC parameter describes the "TSU" class filter ($) and the "STC" class filter (#). But, SDSF JC$ command or JC# command is not processed correctly.
When issuing the JC$ to access the Job Class (JC) panel, only the "TSU" class should be shown. However, the "STC" class is shown instead.
Similarly, the JC# command shows the "TSU" class but should be the "STC" class.
Finally, SDSF APAR PH26541 (June 2020) has been taken to correctly process both JC# and JC$ commands as documented in the aforementioned SDSF manual. PTFs were applicable to both z/OS V2R3 and V2R4 while the problem existed even for prior z/OS releases.
If you depend on the incorrect behavior for SDSF JC# or JC$ command, it's time to update your operation as described in the SDSF manual once the PTF is applied.
BTW, apart from the above topic, you might need a PTF for SDSF APAR PH25772 (June 2020) to resolve an unique problem in z/OS V2R4.
In z/OS V2R4 SDSF, the STC class filter (#) on the I (Input Queue) or ST (Status Display) command is incorrectly processed. When the # is the first or only class specified, both I# and ST# commands filter TSU jobs rather than STC jobs.
For example, ST# will give you the exact same results as ST$. ST#A will give you the same results as ST$A (will give you TSO and class A jobs). STA# will process correctly and give you class A jobs and STC jobs.
As a problem conclusion, SDSF has been updated to correctly process the STC class parameter (#) when entered on the the I or ST commands.
Hope it helps you.
Thanks!