Well - on a whim - I put this question to Facebook's Meta.ai:
In z/OS - how does a "Signal Interface Routine" know that the
COND_SETUP service has been called, so it can "push back" a signal?
and it gave me this answer:
In z/OS, a Signal Interface Routine (SIR) can determine if the COND_SETUP
service has been called by checking the value of the Conditional Setup
Indicator (CSI) in the Signal Environment Block (SEB).
Here's how it works:
1. When COND_SETUP is called, it sets the CSI in the SEB to a non-zero
value.
2. The SIR can then check the CSI value in the SEB to determine if
COND_SETUP
has been called.
3. If the CSI value is non-zero, the SIR knows that COND_SETUP has been
called and can "push back" the signal by updating the signal
information
in the SEB and returning a specific completion code to the operating
system.
By checking the CSI value, the SIR can determine whether COND_SETUP has been
called and take appropriate action to handle the signal.
And, I followed up with this question:
How do you find the SEB within the "Signal Interface Routine"?
to get this response:
Within a Signal Interface Routine (SIR), you can find the Signal Environment
Block (SEB) through the Register 1 (R1) parameter passed to the SIR.
Here's how:
1. The operating system passes the address of the SEB in Register 1 (R1)
when invoking the SIR.
2. Within the SIR, you can access the SEB by loading the address from R1
into a register, such as R4, using the instruction: L R4,0(1,R1)
3. Once you have the address of the SEB in R4, you can access the various
fields within the SEB, including the Conditional Setup Indicator (CSI),
using offset calculations and load instructions.
For example: L R5,CSI_OFFSET(0,R4) would load the value of the CSI field into
R5, assuming CSI_OFFSET is a defined constant representing the offset of the
CSI field within the SEB.
By accessing the SEB through R1, you can retrieve the necessary information
to process the signal and perform the required actions within the SIR.
Thank you AI!
- Dave Rivers -
--
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