Having the PC routine above the bar is not the same as having the single PC instruction above the bar that is used to invoke the PC routine, wherever the PC routine may be loaded. All that the PC instruction does is generate a number and then use that number to index through the linkage table structure to find the address of the routine to be called. Also executing the PC instruction in 64-bit addressing mode causes a 63-bit return address to be stored somewhere (depending on whether stacking is used or not), so a return to the instruction after an above-the-bar PC is possible. What happens inside the called routine is an independent topic.
Bill Fairchild -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Bob Shannon Sent: Monday, July 18, 2011 9:46 AM To: IBM-MAIN@bama.ua.edu Subject: Re: Lines, Bars and ... mini-bars??? >He did not say the PC instruction will not work above the bar The Entry Table Entry for a PC routine has not been expanded to 64 bits. Until it is, a PC routine cannot be above the Bar. It appears that Amode 64 is supported (but not documented) but the PC routine cannot reside above the Bar Bob Shannon ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
