Lloyd, According to the z/Architecture Principles of Operation, SA22-7832-09, page 5-9, all 64 bits of the index register are used.
My interpretation is that it is not the AMODE, but the architectural mode that affects the interpretation of the index register. On a z/Architecture-capable machine, in ESA mode, bits 0-31 of the index register are ignored, and bits 32-63 are used. On a z/Architecture-capable machine, in z/Architecture mode, bits 0-63 of the index register are used. Perhaps someone from IBM can confirm or dispute this interpretation. John P. Baker President NGSSA, LLC -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Lloyd Fuller Sent: Thursday, November 29, 2012 7:29 AM To: [email protected] Subject: Re: Usefullness (or not) of STOC/LOC instructions? The latter can also run into issues in AMODE 64. The index register is always 32 bits, not 24, 31, or 64 depending upon AMODE. Waste the extra nano-second, use the comma. It is meaningful. Lloyd ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
