Macro code was deprecated with CICS 1.5 in the early 80s, though it stayed
around for many years after that.

On Wed, Jul 26, 2023 at 9:39 AM Pommier, Rex <[email protected]>
wrote:

> And then there's this handy little tool from MacKinney systems called MLI
> that allows macro level code to still run in 2023!  Was macro code
> deprecated around 1988?
>
> Rex
>
> -----Original Message-----
> From: IBM Mainframe Discussion List <[email protected]> On Behalf
> Of Crawford Robert C (Contractor)
> Sent: Wednesday, July 26, 2023 9:26 AM
> To: [email protected]
> Subject: [EXTERNAL] Re: [EXT] Ars Technica: The IBM mainframe: How it runs
> and why it survives
>
> That's good to know.  I always assumed CICS had a storage manager because
> it was faster than GETMAIN/FREEMAIN.
>
> I remember the old macro interface and it was a mess, especially with
> application programs addressing system control blocks directly.  Not to
> mention how weird macro code looked in the middle of a PL/1 program.  IBM
> was wise to deprecate the interface even though the conversion caused pain.
>
> Robert Crawford
> Abstract Evolutions LLC
> (210) 913-3822
>
> -----Original Message-----
> From: IBM Mainframe Discussion List <[email protected]> On Behalf
> Of Colin Paice
> Sent: Wednesday, July 26, 2023 8:57 AM
> To: [email protected]
> Subject: Re: [EXT] Ars Technica: The IBM mainframe: How it runs and why it
> survives
>
> CICS was "common code" between VS1 and DOS/VS(E) DOS/VS (I used to build
> it for CICS development), with AIF.. ANOP  statements around VS1/DOS
> specific code.  DOS/VS did not have the same facilities as VS1, so CICS had
> to be written to the lowest level of code.
>
>
> On Wed, 26 Jul 2023 at 14:45, Crawford Robert C (Contractor) <
> [email protected]> wrote:
>
> > Yes, CICS has problems with shared memory which it mitigates through
> > storage protection and transaction isolation.  IMS MPR's are not
> > entirely immune from this either as a bad array index or funky pointer
> > can wipe out acres of storage and leave a region inoperative.  I saw
> > some MPR loops that were so tight all we could do is put the address
> > space in a WLM penalty box and bring down the control region at night.
> >
> > I also remember that canceling an MPR was always a last resort
> > because, if the interface was in the wrong state, it could bring down
> > the control region.
> >
> > CICS has had open TCB's for decades now that enable application
> > programs to use any old OS interface they want.  Global User Exits
> > (GLUE's) provide clean interfaces for all sorts of system software and
> DBMS' .
> >
> > When I worked in an IMS dominated shop we always had to carefully
> > watch CSA and ECSA.  Sure, CICS regions can use a lot of memory, but
> > you can always buy more real storage.
> >
> > MPR's, which I saw implemented as batch jobs, do provide great
> > isolation between processes and allow for exploitation of OS services.
> > CICS duplicates a lot of OS services but why have a storage manager on
> > top of a storage manager?  On the other hand, keeping things going
> > smoothly means running dozens, if not hundreds, of MPR's to support a
> > transaction rate that could be executed by a fourth as many CICS regions.
> >
> > MPR's are basically batch jobs getting fed one message at a time.
> > This implementation requires a lot of bolt-ons (e.g., IMS Connect)
> > which come with their own quirks.  I've also seen it require weird
> > solutions for fitting synchronous processes to an asynchronous system.
> >
> > I did like MFS because it provides true device independence.  It
> > allowed us to drive 3270 transactions with LU6.1 messages from CICS
> > without any changes.
> >
> > I could also go on about dynamic resource definition, automated
> > emergency restart (without using automation), better system management
> interfaces.
> > Not to mention quicker, cleaner and native implementations of newer
> > technologies.
> >
> > IMO, CICS is much more flexible and better positioned to continue
> > processing in the modern world.
> >
> > Robert Crawford
> > Abstract Evolutions LLC
> > (210) 913-3822
> >
> > -----Original Message-----
> > From: IBM Mainframe Discussion List <[email protected]> On
> > Behalf Of Schmitt, Michael
> > Sent: Tuesday, July 25, 2023 9:38 AM
> > To: [email protected]
> > Subject: Re: [EXT] Ars Technica: The IBM mainframe: How it runs and
> > why it survives
> >
> > So CICS is no longer doing cooperative multitasking within each AOR,
> > and thus requiring CICS versions of OS commands to prevent wait states
> > from freezing the entire AOR? A CICS program can do direct GETMAINs,
> > LOADS, abends, rather than use CICS commands? CICS no longer requires
> > special versions of tools (e.g. debugger, abend dump management) and
> > instead can use the same tools as batch programs? A CICS programmer no
> > longer needs to learn a long list of CICS commands and EXEC CICS
> > syntax? A CICS region no longer contains the storage from all of the
> > transactions currently running and is now only one transaction in the
> > region at a time? CICS transactions can no longer stomp on each other's
> memory?
> >
> > Great, I did not know that.
> >
> > IMS/TM uses the operating system for multitasking. There are no IMS/TM
> > specific tools. An IMS/TM programmer only needs to know two commands,
> > one to get a message and another to send it. IMS transaction abends
> > look
> > (almost) exactly like a batch abend. IMS programs have no restrictions
> > on OS facilities. An IMS program can even do an STIMER (WAIT) without
> > affecting any other transaction processing. Because, it uses the OS to
> > do
> > *preemptive* multitasking, like a modern operating system.
> >
> > -----Original Message-----
> > From: IBM Mainframe Discussion List <[email protected]> On
> > Behalf Of Crawford Robert C (Contractor)
> > Sent: Tuesday, July 25, 2023 8:14 AM
> > To: [email protected]
> > Subject: Re: [EXT] Ars Technica: The IBM mainframe: How it runs and
> > why it survives
> >
> > Sorry, I worked in a shop that had both and I can tell you CICS is way
> > more flexible, modern and performed better.
> >
> > I will give you this:  IMS is a great piece of 90's technology.
> >
> > Robert Crawford
> > Abstract Evolutions LLC
> > (210) 913-3822
> >
> > -----Original Message-----
> > From: IBM Mainframe Discussion List <[email protected]> On
> > Behalf Of Schmitt, Michael
> > Sent: Monday, July 24, 2023 11:43 AM
> > To: [email protected]
> > Subject: [EXT] Ars Technica: The IBM mainframe: How it runs and why it
> > survives
> >
> > Ars Technica published a deep-dive explainer of modern IBM mainframes:
> >
> >
> > https://urldefense.com/v3/__https://arstechnica.com/information-techno
> > logy/2023/07/the-ibm-mainfra__;!!KjMRP1Ixj6eLE0Fj!rNa-SaGicFiF68vSt9OY
> > ExPvljK4ShqzUuxW9fAMxwJNqupUj5wjtWSiwuUmUuPL5Zz9fb1K1RGcyBzezNfMZS69W9
> > lqPfp6mPyI$
> > me-how-it-runs-and-why-it-survives/
> >
> >
> > I’d quibble with the application server topic that talks about CICS
> > with no mention of IMS/TM. CICS is to IMS as Windows 3.1 is to Windows
> > 10.  😊
> >
> >
> >
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-- 
Jay Maynard

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