> How does STOP work? >From a programmer's point of view, it sets a flag and posts an ECB.
> Is MODIFY similar? Yes, both are quite similar in how they work. Modify is a flag plus the text of the command. AFAIR Stop is just a flag, but I might well be wrong and I am too lazy to look it up right now. > Does either schedule an RB to a task? Don't think so, but not sure. > What happens if that task is not prepared to deal with such an RB? z/OS "knows" whether a program has gone through the motions of telling z/OS it was prepared to accept console commands. If not, z/OS rejects the command. If the program tells z/OS it can process commands but fails to do so, then the command "just sits there." z/OS knows how many "stacked" un-processed commands a program can accept -- one, for any program I have ever written -- and rejects new commands in excess of that. > Which is older, STOP or MODIFY? Well, both are in the 1968 manual I cited earlier in this thread. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Paul Gilmartin Sent: Wednesday, December 05, 2012 5:37 AM To: [email protected] Subject: Re: Historical question regarding the stop command On Dec 5, 2012, at 05:32, Martin, Larry D wrote: > > I believe the reason for the "Start in order to Stop" process is required in order to stop Unix Daemons that are running as a part of the process. I agree that the code to handle STOP and MODIFY commands is quite simple, but I don't have any experience starting and stopping Daemons. > The UNIX analogue is "kill" which sends any of several signals to a process. For example, SIGINT tells processes designed to handle it to prompt or seek additional command information elsewhere. SIGTERM warns a process of imminent system shutdown; I believe that in the spirit of POSIX, z/OS shutdown should send SIGTERM to dubbed tasks; others reading this will feel strongly otherwise. SIGINT and SIGTERM are fatal if not handled. SIGKILL is unconditionally fatal (think FORCE, but not so destructive). SIGHUP (HangUP) tells a process that its controlling terminal has been disconnected. Etc. A couple signals are reserved for user/ISV definition in any supplied application; often used for debugging. How does STOP work? Is MODIFY similar? Does either schedule an RB to a task? What happens if that task is not prepared to deal with such an RB? Which is older, STOP or MODIFY? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
