Concurrently updating an IODF

Both users UserA and UserB start on the Channel Subsystem List of the same IODF. UserA invokes action Change on CSS 1 and UserB updates Maximum Devices in SS0 for CSS2 and CSS3 from 65280 to 64512 and additionally invokes action Delete on the same CSS 1 maybe a few seconds later.

                      UserA:                  |                      UserB:
                                              |
            Channel Subsystem List            |             Channel Subsystem List
                                              |
  Processor ID . . . : BBBX                   |   Processor ID . . . : BBBX
                                              |
    CSS Devices in SS0    Devices in SS1      |     CSS Devices in SS0    Devices in SS1
  / ID  Maximum + Actual  Maximum + Actual    |   / ID  Maximum + Actual  Maximum + Actual
                                              |
  _ 0   65280     28      65535     0         |   _ 0   65280     28      65535     0
 c  1   65280     28      65535     0         |  d  1   65280     28      65535     0
  _ 2   65280     0       65535     0         |   _ 2   64512     0       65535     0
    3   65280     0       65535     0         |   _ 3   64512     0       65535     0

HCD displays panel Change Channel Subsystem for UserA while UserB receives message CBDA340I. When UserB returns from the Message List to the Channel Subsystem List, the panel is not refreshed and UserB's updates are kept on the screen. Thus, UserB can retry his update request several times until UserA releases the lock on the IODF.

                      UserA:                  |                      UserB:
                                              |
           Change Channel Subsystem           |                    Message List
                                              |
                                              |
  Specify or revise the following values.     |  Messages are sorted by severity.
                                              |  Select one or more, then press Enter.
  Processor ID . . . . . . : BBBX             |
  Channel subsystem ID . . : 1                |  / Sev Msg. ID Message Text
                                              |  _ E CBDA340I IODF USERA.IODF00.TEST.WORK
  Description  . . . . . . . ________________ |  # is currently being updated
                                              |  # by HCD user USERA on system
  Maximum number of devices                   |  # SCLM.
    in subchannel set 0  . . 65280  +         |
    ...                                       |