Hi,
Thanks for all the responses. It looks like there is no practical way to detect
unintentional run-time access to page zero. Programs range from 50+ years old
to quite recent. a recompile of everything with FLAG(PAGE0) and fixing obvious
errors, followed by a test environment run of a few months under zOS 2.5 to
catch any run-time errors seems to be the best way forward.
Again Thanks all.
Regards,Syama
On Wednesday, March 29, 2023 at 02:53:48 AM GMT+13, Gary Weinhold
<[email protected]> wrote:
Early on the OP said that program that were OK before (I assume meaning that
they passed testing) were now (with z/OS 2.5) not OK, but not abending. He had
evidently tracked enough errors to accessing page 0 instead of their intended
target that he's worried there are more.
This is not unique to assembler, although it may be in the OP's case. I've
written COBOL and REXX programs to chase pointers to find control blocks. If I
don't check that my pointers are non-zero, I could have the same type of
errors. And these programs are not production programs, so failures are
inconvenient, not catastrophic.
Gary Weinhold
Senior Application Architect
DATAKINETICS | Data Performance & Optimization
Phone:+1.613.523.5500 x216
Email: [email protected]
Visit us online at www.DKL.com
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________________________________
From: IBM Mainframe Assembler List <[email protected]> on behalf
of Retired Mainframer <[email protected]>
Sent: March 27, 2023 21:21
To: [email protected] <[email protected]>
Subject: Re: Blocking Low core access from Assembler programs
You are asking how to implement a solution but you have not told us what
problem you are trying to solve. What is the real issue with this program
accessing data in page 0?
-----Original Message-----
From: IBM Mainframe Assembler List <[email protected]> On Behalf
Of syama prasad
Sent: Monday, March 27, 2023 3:48 PM
To: [email protected]
Subject: Blocking Low core access from Assembler programs
Hi,
Is it possible to force an Assembler program to hit an access error if it
tries to load data from the low core (page starting from address
zero)?Assembler *PROCESS FLAG(PAGE0) " helps to find cases like MVC
TARGET,1But will it be possible to have a run time detection and possibly a
dump if the program tries to do things likeLA R5,1MVC TARGET,0(R5)Basically,
any way to restrict access of an application program to PSA- first control
block?
Regards,Syama
