"In addition, there is one action parameter, VALIDATE" says the documentation. That, coupled with "VALIDATE has no effect if the unit address has no physical device attached" is a pretty strong indication that there is an actual effect from VALIDATE.
"Use the dump selection parameters, to define the contents of the display. Beyond the basic status information, you can specify which of the following MVS™ system control blocks, and/or what information acquired directly from the following device information buffers, to display in hexadecimal format. The system control blocks are UCB, DCE, SSSCB, DPCT and RDFEATS. If you specify the parameter NOIO, the display will show only the storage resident information in the MVS control blocks; the command will not issue any I/O to the selected devices. The device information buffers are RDC, RCD, and SNSS." If I were to guess, I'd say that UCB, DCE, SSSCB, DPCT and RDFEATS are all candidates to be "updated" (validated) from RDC, RCD (don't you just love when you see TLCs in the same paragraph which are anagrams of each other?) and SNSS. Unless NOIO is specified. However, I assume the purpose of the question is not to rely on guesses. From reading the brief documentation, I'd for sure say VALIDATE may update something. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN