What Controls the Creation Date on QTEMP Libraries

QTEMP libraries are not reused across IPLs. New QTEMP libraries are created on each IPL as they are needed. Work Management code calls Librarian code to create a QTEMP library when the job structure is created. After a job ends, the QTEMP library associated with the job is now available for use by another job.
The creation date shown on the DSPOBJD command should be the actual creation date of when the library was created. Because the QTEMP library could be reused, the date/time could be very different from the date/time of when the job started. Therefore, the QTEMP creation time is the time that a previously created job structure is first used after an IPL or when a new job structure is created.