Re: Specifhing the ENVBLOCK (was: Just PDSE)

2023-04-12 Thread Seymour J Metz 
The point is that while lookup only involves a chain, nothing in the 
documentation even hints that validation only involves the chain for the 
current TCB.


From: IBM Mainframe Discussion List  on behalf of 
Attila Fogarasi 
Sent: Wednesday, April 12, 2023 7:42 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: Specifhing the ENVBLOCK (was: Just PDSE)

Separate chains per TCB, so linear chain within TCB but no correlation
between TCBs.  Programs that use conflicting or incompatible environments
across multiple TCBs are on their own :)

On Mon, Apr 10, 2023 at 10:54 PM Seymour J Metz  wrote:

> "However, separate chains within a single address space are independent."
> doesn't sound like a single chain.
>
> 
> From: IBM Mainframe Discussion List  on behalf
> of Paul Gilmartin <042bfe9c879d-dmarc-requ...@listserv.ua.edu>
> Sent: Sunday, April 9, 2023 5:16 PM
> To: IBM-MAIN@LISTSERV.UA.EDU
> Subject: Re: Specifhing the ENVBLOCK (was: Just PDSE)
>
> On Sun, 9 Apr 2023 20:41:33 +, Seymour J Metz wrote:
>
> >Curse you, OCO!
> >
> >I suspect that validating a potential ENVB address requires running a
> tree rather than just a list.
> >
> <
> https://www.ibm.com/docs/en/zos/2.5.0?topic=environments-chains-how-are-located
> >
> shows only linear chains.  So there can't be other kids of trees.
>
> --
> gil
>
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Re: Specifhing the ENVBLOCK (was: Just PDSE)

2023-04-12 Thread Attila Fogarasi 
Separate chains per TCB, so linear chain within TCB but no correlation
between TCBs.  Programs that use conflicting or incompatible environments
across multiple TCBs are on their own :)

On Mon, Apr 10, 2023 at 10:54 PM Seymour J Metz  wrote:

> "However, separate chains within a single address space are independent."
> doesn't sound like a single chain.
>
> 
> From: IBM Mainframe Discussion List  on behalf
> of Paul Gilmartin <042bfe9c879d-dmarc-requ...@listserv.ua.edu>
> Sent: Sunday, April 9, 2023 5:16 PM
> To: IBM-MAIN@LISTSERV.UA.EDU
> Subject: Re: Specifhing the ENVBLOCK (was: Just PDSE)
>
> On Sun, 9 Apr 2023 20:41:33 +, Seymour J Metz wrote:
>
> >Curse you, OCO!
> >
> >I suspect that validating a potential ENVB address requires running a
> tree rather than just a list.
> >
> <
> https://www.ibm.com/docs/en/zos/2.5.0?topic=environments-chains-how-are-located
> >
> shows only linear chains.  So there can't be other kids of trees.
>
> --
> gil
>
> --
> For IBM-MAIN subscribe / signoff / archive access instructions,
> send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
>
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Re: Specifhing the ENVBLOCK (was: Just PDSE)

2023-04-10 Thread Seymour J Metz 
"However, separate chains within a single address space are independent." 
doesn't sound like a single chain.


From: IBM Mainframe Discussion List  on behalf of 
Paul Gilmartin <042bfe9c879d-dmarc-requ...@listserv.ua.edu>
Sent: Sunday, April 9, 2023 5:16 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: Specifhing the ENVBLOCK (was: Just PDSE)

On Sun, 9 Apr 2023 20:41:33 +, Seymour J Metz wrote:

>Curse you, OCO!
>
>I suspect that validating a potential ENVB address requires running a tree 
>rather than just a list.
>
<https://www.ibm.com/docs/en/zos/2.5.0?topic=environments-chains-how-are-located>
shows only linear chains.  So there can't be other kids of trees.

--
gil

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Re: Specifhing the ENVBLOCK (was: Just PDSE)

2023-04-09 Thread Paul Gilmartin 
On Sun, 9 Apr 2023 20:41:33 +, Seymour J Metz wrote:

>Curse you, OCO!
>
>I suspect that validating a potential ENVB address requires running a tree 
>rather than just a list.
>

shows only linear chains.  So there can't be other kids of trees.

-- 
gil

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Re: Specifhing the ENVBLOCK (was: Just PDSE)

2023-04-09 Thread Seymour J Metz 
Curse you, OCO!

I suspect that validating a potential ENVB address requires running a tree 
rather than just a list.


--
Shmuel (Seymour J.) Metz
http://mason.gmu.edu/~smetz3


From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of 
Paul Gilmartin [042bfe9c879d-dmarc-requ...@listserv.ua.edu]
Sent: Sunday, April 9, 2023 3:11 PM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Specifhing the ENVBLOCK (was: Just PDSE)

(Subject: changed: this has drifted far from"PDSE")

On Sun, 9 Apr 2023 09:50:44 +, Seymour J Metz wrote:

>Chapter 12. TSO/E REXX programming services
>
Thanks.  Eek!  TMI.  Where I see:
Entry specifications
For the IRXEXCOM routine, the contents of the registers on entry are:
Register 0  Address of an environment block (optional)

It should clarify that with "see Parameter 5 (below)"
Where it says:
... However, IRXEXCOM does not check whether the address is valid.
Ouch!
And the concern raised earlier that many languages don't allow control
of R0 is serious.  REXX should provide standard CALL interfaces.

The Services book mentions IKJCT441 as an alternative.  However:
IKJCT441 uses the REXX direct interface (rather than the symbolic
interface).  Why this serious restriction?  Compatibility with CLIST
limitations?

Is there a callable service that returns a *valid* EXECBLOCK address?

>"f you do not specify an address in the environment block address parameter, 
>the TSO/E REXX routine
>checks register 0 for the address of an environment block. If register 0 
>contains the address of a
>valid environment block, the routine runs in the environment represented by 
>that environment block.
>If the address is not valid, the routine locates the current non-reentrant 
>environment and runs in that
>
There is much mention of environment chains.  How are those chains rooted?
It may not matter if it has no supported user interface.

How does it check for validity?  Merely verifying the identifier "ENVBLOCK"?
Or does it verify that block exists in a chain.

>environment. If register 0 contains a 0, the routine immediately searches for 
>the last non-reentrant
>environment created, thereby eliminating the processing required to check 
>whether register 0 contains a
>valid environment block address."

So it's quicker to search a list than validate a passed address!?

--
gil

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Specifhing the ENVBLOCK (was: Just PDSE)

2023-04-09 Thread Paul Gilmartin 
(Subject: changed: this has drifted far from"PDSE")

On Sun, 9 Apr 2023 09:50:44 +, Seymour J Metz wrote:

>Chapter 12. TSO/E REXX programming services
>
Thanks.  Eek!  TMI.  Where I see:
Entry specifications
For the IRXEXCOM routine, the contents of the registers on entry are:
Register 0  Address of an environment block (optional)

It should clarify that with "see Parameter 5 (below)"
Where it says:
... However, IRXEXCOM does not check whether the address is valid. 
Ouch!
And the concern raised earlier that many languages don't allow control
of R0 is serious.  REXX should provide standard CALL interfaces.

The Services book mentions IKJCT441 as an alternative.  However:
IKJCT441 uses the REXX direct interface (rather than the symbolic
interface).  Why this serious restriction?  Compatibility with CLIST
limitations?

Is there a callable service that returns a *valid* EXECBLOCK address?

>"f you do not specify an address in the environment block address parameter, 
>the TSO/E REXX routine
>checks register 0 for the address of an environment block. If register 0 
>contains the address of a
>valid environment block, the routine runs in the environment represented by 
>that environment block.
>If the address is not valid, the routine locates the current non-reentrant 
>environment and runs in that
>
There is much mention of environment chains.  How are those chains rooted?
It may not matter if it has no supported user interface.

How does it check for validity?  Merely verifying the identifier "ENVBLOCK"?
Or does it verify that block exists in a chain.

>environment. If register 0 contains a 0, the routine immediately searches for 
>the last non-reentrant
>environment created, thereby eliminating the processing required to check 
>whether register 0 contains a
>valid environment block address."

So it's quicker to search a list than validate a passed address!?

-- 
gil

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