I have a control block chain in CSA above the BAR that is updated from multiple
address spaces with a first and last pointer. The last entry in the chain has a
next = 0. If there are no entries in the chain the first and last pointer = 0.
I seem to be adding two entries to the beginning of the chain at the same time
because rarely one of the control blocks is never freed and it always has a
next pointer of zero.
I use the following code to add a control block to the end of the chain (always
add to the end of the chain):
FIRST DS D
LAST DS D
DOX378 DS 0H
LG R6,LAST
*C IF FIRST AND LAST EQ 0
*C SET FIRST AND LAST = NEW CB ADDRESS
XGR R4,R4
XGR R5,R5
LGR R2,R8 (R8: ADDRESS OF CB)
LGR R3,R8
CDSG R4,R2,FIRST IF FIRST & LAST 0, STM 2,3,FIRST
BC 4,ELIFX076
*C ELSE
BC 8,EDOX378
ELIFX076 DS 0H
*C IF LAST = LAST (R6)
*C SET LAST = POINTER_TO_NEW_ (R8)
*C SET NEXT.OF.LAST.ONCHAIN= POINTER_TO_NEW_ (R8)
STG R6,OPERAND1 (COMPARISON VALUE)
STG R8,OPERAND1R (REPLACEMENT VALUE)
LA R0,CSDSTG
LGR R3,R8
LA R4,LAST LAST IS IN CSA
STG R4,OPERAND6
DROP R8
USING CB,R6
LA R4,NEXT NEXT IS IN CSA
STG R4,OPERAND4
STG R8,OPERAND3
STG R8,OPERAND5
PLO 0,LAST,0,PL
* THE FIRST-OPERAND COMPARISON VALUE AND THE SECOND OPERAND ARE
* COMPARED. IF THEY ARE EQUAL, THE FIRST-OPERAND REPLACEMENT VALUE
* IS STORED AT THE SECOND-OPERAND LOCATION, AND THE THIRD OPERAND IS
* STORED AT THE FOURTH-OPERAND LOCATION. THEN, THE FIFTH OPERAND IS
* STORED AT THE SIXTH-OPERAND LOCATION.
EDOX378 DS 0h
Note: I think I could use a CSSTG PLO but this should work and I don’t want to
break what normally works since this is production code. I have looked at this
code until my eyes are falling out. Does anyone see a flaw in this logic?
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