File-update triggering

File-update triggering is more complex because, as mentioned previously, in general, the z/OS® operating system does not maintain information for files that could be used as a way of recognizing that the file changed. The z/OS Launcher will infer a change of a PDS or PDS/E member by recognizing the change in its location, TTR, or pointer.

File-update triggering is allowed for PDS or PDS/E members, but not sequential files. There is no straightforward way to check for sequential file updates.

The following process repeats until the specified event is triggered. The process awaits a specified file to be updated and when it recognizes that it has been updated, by a successful directory read attempt, it triggers execution of an event.

To trigger on an updated file:

  1. Retrieve the current TTR information for the PDS or PDS/E member or members by reading the directory.
  2. Save the retrieved information.
  3. Repeat the loop until the process recognizes that the file has been updated.
    • Get the TTR information.
    • If the TTR information has changed, the event is triggered and the TTR is updated.
    • If the TTR information has not changed, the process repeats the loop to check for file updates.