Hi Folks,
A while back, there was a discussion on IBM-Main about how to
access the ECT (Environment Control Table) which is a TSO control block
pointed to by the CPPL (Command Processor Parameter List) pointed to by
Register 1 when a TSO command gets control.
Binyamin Dissen pointed out that there is a pointer to the ECT at
+X'100' in the TSO Relogon Buffer. This got me interested in the
Relogon Buffer. The relogon buffer is pointed to from the PSCB, using
address field PSCBRLGB at PSCB+X'30'.
We now have developed several tools to manipulate the thing. They
can be found on the CBT Tape Updates page www.cbttape.org/updates.htm on
File 731. Please bear in mind that the data portion of the relogon
buffer should normally contain only LOGON or LOGOFF commands, to my
knowledge.
To display what is in the RELOGON buffer, we have the SHOWRLGB TSO
command. An example of an empty TSO Relogon Buffer is shown below:
TSO RELOGON BUFFER
--- ------- ------
Relogon Buffer Address: 00007EF8
0100 0000 Header Dec
+0
4040404040404040404040404040404040404040404040404040404040404040404040
+35
4040404040404040404040404040404040404040404040404040404040404040404040
+70
4040404040404040404040404040404040404040404040404040404040404040404040
+105
4040404040404040404040404040404040404040404040404040404040404040404040
+140
4040404040404040404040404040404040404040404040404040404040404040404040
+175
4040404040404040404040404040404040404040404040404040404040404040404040
+210
4040404040404040404040404040404040404040404040404040404040404040404040
+245
40404040404040 ECT Addr: 0000BB88 ECTLOGF is OFF
Another tool we have, is a TSO command called BYE, to load the
Relogon Buffer with anything, and to turn on the ECTSWS switch with
X'10', so that when you go to TSO READY mode, you will automatically be
logged off, and the contents of the Relogon Buffer will be executed.
For example, if you execute the TSO command: BYE LOGON yourid/password
and you go to READY mode, then your session will be logged off, and a
new LOGON with your password, will be executed. To ONLY turn OFF the
ECTSWS,X'10' switch, we have a NOLOGOF command. To ONLY turn it back ON
again, we have a YESLOGOF command. These four commands should give you
complete control of the Relogon Buffer.
I forgot to mention something. If you execute the TSO command BYE
with NO OPERANDS, you re-initialize the command buffer, and you turn the
ECTSWS,X'10' switch OFF. So you can easily undo what you have done
using the BYE command, WITH operands.
I hope that these tools will be constructively useful for some of
you. Use them well, but use them carefully.
All the best of everything to all of you.
Sincerely, Sam
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