That was the first place I looked. It mentions key 0 and supervisor mode, but no more.
-- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Mike Myers [m...@mentor-services.com] Sent: Thursday, November 5, 2020 3:03 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Documentation for environment of EXCP appendages Seymour: I found there is documentation online. I searched for: IBM z/OS EXCP appendage and came back with a hit: EXCP and EXCPVR Appendages in z/OS DFSMSdfp Advanced Services It has been several years, but I have explored use of the appendages dating back to OS/360, where I used to teach the internals of ISAM and BDAM to PSRs. The neatest use was PCI, where the interrupt coming from a specific CCW in a channel program notified the appendage of the point where the channel program was executing and the appendage could make changes to the channel program in response. In general, the appendage could choose to let the channel program end or could add more CCWs to the channel program to continue the I/O operation in response to new information obtained in data read or in response to new related requests from system activity. The main usage was "self modifying channel programs" as in ISAM and BDAM and in "seldom ending channel programs" more recently in ASM, where a channel program already running and performing paging I/O could add new page I/O to the running channel program as more page in or page out requests occurred. Mike Myers On 11/4/20 10:52 PM, Seymour J Metz wrote: > I'm editing the wiki article on EXCP, and I'd like to correct what it says > about appendages. I couldn't find any documentation on the environment in > which appendages run, although I'm fairly certain that it's PASN, SRB and all > the usual suspects. Wiki politics being what they are, it's a lot easier if I > provide a citation for everything. > > > > -- > Shmuel (Seymour J.) Metz > http://mason.gmu.edu/~smetz3 > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
