Customer have already installed Strobe v 21 migating for V18 .
They followed instructions from the Strobe Manual to migrate and can't find member $09MGSTR in any Library.

Task 4.2.2 Verify and Execute the $09MGSTR job
Important

Note that $07ALSTR creates the queue, log, system, group, and history data sets in addition to the Strobe startup procedures. $09MGSTR will not attempt to allocate these data sets if they already exist.

After running the $07ALSTR job, run the $09MGSTR job if you want to migrate the queue data set, group data set, and AutoStrobe data set from a previous release to the current release.