On Wed, 12 Feb 2025 at 20:24, Joseph Reichman <
[email protected]> wrote:
> I know there is a way when you scan the TIOT and find a DDNAME entry how
to
> associate it with a DCB
Just to be clear, there is no way to find a DCB that isn't open - that's
completely unknown to the system. It may not even exist yet.
> I think you save the first TIOT entry then while scanning you keep track
of
> the offset to the DDNAME you are looking for then get the DEB from the
TCB
> and get the DCB from the DEB and compare DCBTIOT to that offset
>
>
> If not equal, you get the next DEB and do the same
Assuming your DCB of interest is open, then this ancient snippet should
work in an old-style environment, i.e. no XTIOT, and in 24- or 31-bit mode.
Of course there are newer instructions like LLH that could be used.
======
L R4,PSATOLD-PSA -> Current TCB Assumes you want the
current one...
USING TCB,R4
* L R4,TCBJSTCB -> Job Step TCB ...or maybe the Job
Step one
L R5,TCBDEB -> 1st DEB on chain
BZ NO_DEB No DEBs
USING DEBBASIC,R5
SR R6,R6 Clear high byte for 24-bit addressing
NEXT_DCB ICM R6,B'0111',DEBDCBB -> DCB or ACB
BNZ CHK_DCB Got one
NEXT_DEB ICM R5,B'0111',DEBDEBB -> Next DEB
BZ NO_DEB DEB search exhausted
B NEXT_DCB Try next DCB
CHK_DCB DS 0H
USING IHADCB,R6
TM DCBDSRG2,DCBACBM Is it an ACB?
BO NEXT_DEB Yes - not interested
SR R7,R7 Clear for halfword stuff
ICM R7,B'0011',DCBTIOT Get DD entry offset (not LH!)
AL R7,TCBTIO Add TIOT address
CLC =CL8'ddname of interest',TIOEDDNM-TIOENTRY(R7) ?
BNE NEXT_DEB No - try further
* Found it
...
NO_DEB Not found - issue msg
======
No guaranties, etc.
Tony H.
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