Business needs. The key questions are
What is the oldest OS we have to support
What is the oldest processor we have to support.
Long ago in a galaxy far away I controlled dual passing with SYSPARM, tested by
my private macros.
--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3
עַם יִשְׂרָאֵל חַי
נֵ֣צַח יִשְׂרָאֵ֔ל לֹ֥א יְשַׁקֵּ֖ר
________________________________________
From: IBM Mainframe Assembler List <[email protected]> on behalf
of Tom Marchant <[email protected]>
Sent: Monday, April 15, 2024 2:49 PM
To: [email protected]
Subject: Re: Complex immediate fields
Charles is right. IILF was first documented in the -08 level of the POO, for
the z114/z196. z/OS 2.2 was the last release to run on that hardware, and has
been unsupported since 2020-09-30. The extended mnemonic LFI was added later,
but that isn't relevant.
I don't understand the reluctance to use newer instructions when they are
included in the minimum requirement for the operating system.
--
Tom Marchant
On Mon, 15 Apr 2024 09:09:06 -0700, Charles Mills <[email protected]> wrote:
>If you are running "sometimes" on older hardware I think you have a greater
>risk from unsupported z/OS than from unsupported instructions.
>
>I'm not sure, but I think that IILF came along no later than the zEC12. Any
>machine older than the zEC12 only supports z/OS V2R2 and below. V2R2 went out
>of service almost four years ago. If you are running a current z/OS it won't
>run on older hardware.
>
>I also think you are at greater risk of encountering unsupported instructions
>in optimized COBOL 6 code than in hand-built assembler.
>
>And I would never, ever embed data in the instruction stream.
>
>Charles
>
>
>-----Original Message-----
>From: IBM Mainframe Assembler List [mailto:[email protected]] On
>Behalf Of Jon Perryman
>Sent: Sunday, April 14, 2024 11:09 PM
>To: [email protected]
>Subject: Re: Complex immediate fields
>
>> On current hardware there is an IILF (LFI) instruction, and I would like to
>>> use it instead of the XR/ICM sequence.
>
>Before using any modern instructions, ask yourself if they are worth the risk.
>Does your disaster recovery site guarantee this as a minimum machine level.
>Maybe your employer has older machines available in case of capacity problems.
>How about company acquisition. You need to consider the impact.
>
>>Back in he Assembler XF era I would code something like
>> LA R0,L'DEST
>> LA R1,DEST
>> XR R15,R15
>> ICM R15,8,=C' '
>> MVCL R0,R14
>
>Why use LFI when better alternatives for ICM =C' ' have been around forever.
> J bydata
>data dc A(X'40000000',0,L'dest)
>bydata LM R15,R1,data
>
>Since the J instruction only updates the PSW, I'm guessing it will replace the
>update PSW in the previous instruction thus making this a single instruction
>on current hardware but still compatible with older hardware.
>
>Alternatively, there is the NILH instruction which has existed for a couple
>decades.
