In one word - "carefully". Treat every instruction that you execute in key0 as being a candidate to cause the next unscheduled IPL.
I would advise to straddle the code that *actually* requires key0 with a "save current key, go to key0" and then a "restore saved key" sequence - I typically put this in a macro. Make sure that your recovery routines are aware that this code can key-switch and let them restore the environment cleanly. Always be aware of the key of your caller and use it to read and write data owned by them - MVCDK and MVCSK are your friends (also good candidates for macro encapsulation). SAF protect any services that you provide to problem state callers. Never return to your caller with any changes to their execution authority. Test your code (on a test system) with the "dirty regs" and "dirty getmain/freemain" diagnostic traps. -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Scott Ford Sent: Sunday, July 12, 2015 11:57 AM To: [email protected] Subject: Re: SYSTEM KEY Programming Was: IVSK and SPKA With all the discussion, what's the safest way to use key=0 , if it is required ? Scott On Sunday, July 12, 2015, Tom Marchant < [email protected]> wrote: > On Sun, 12 Jul 2015 11:29:01 -0400, Steve Thompson wrote: > > >And hasn't support for DAT OFF (V=R) been dropped? Only the DAT OFF > >nucleus actually runs DAT OFF now? > > V=R doesn't mean DAT off. > Just that virtual addresses map to the same real addresses. > > I've never seen anything that ran V=R, but ADDRSPC=REAL is still > documented. > > -- > Tom Marchant > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to [email protected] <javascript:;> with the message: > INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ================================ Rocket Software, Inc. and subsidiaries ■ 77 Fourth Avenue, Waltham MA 02451 ■ +1 800.966.3270 ■ +1 781.577.4321 Unsubscribe From Commercial Email – [email protected] Manage Your Subscription Preferences - http://info.rocketsoftware.com/GlobalSubscriptionManagementEmailFooter_SubscriptionCenter.html Privacy Policy - http://www.rocketsoftware.com/company/legal/privacy-policy ================================ This communication and any attachments may contain confidential information of Rocket Software, Inc. All unauthorized use, disclosure or distribution is prohibited. If you are not the intended recipient, please notify Rocket Software immediately and destroy all copies of this communication. Thank you. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
