IBM Mainframe Forum

by **steve-myers** » Fri Mar 01, 2013 11:24 am

enrico-sorichetti wrote:... and Yes, I am very picky when it comes to assembler programming ... to avoid surprises I prefer to fill up myself the proper addresses in the <copied> DCBs/DCBEs

for a plain DCB for example
here is my standard <open> sequence

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000098 ...
000104 OPEN ((<DCBREG>),(INPUT)),MF=(E,OPENLST)
000107 ...
...

I'm afraid I didn't pick up on this until just now, but there is another problem in your code snippet: you don't show how you initialize OPENLST. The OPEN macro you show does not set end of OPEN parameter list. Another potential issue is you do not specify a second option after INPUT. Since it's not specified, the macro won't change whatever may be in OPENLST if it's non-zero. Either issue may result in an oops.

I had noticed this ages ago. Somewhere around OS/360 R19 there was a PTF that fixed the end of list issue. It didn't last long; I suspected then someone had code like your code to just change the first entry in a multiple entry parm list. Oops. A PE against the PTF.

by **enrico-sorichetti** » Fri Mar 01, 2013 12:51 pm

you don't show how you initialize OPENLST. The OPEN macro you show does not set end of OPEN parameter list.

the execute form does not do it... the list form does it

the fact that I did not show it, does not mean that I did not take care of it :geek:

everything gets initialized by the MVCL priming the 24BITS working storage

as ... ( source code )

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000014 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
000015 * INITIALIZE WORKING STORAGE
000016 LA R4,WORK
000017 LA R5,WORKL
000018 LA R6,DATA
000019 LA R7,DATAL
000020 MVCL R4,R6
... ... ... ... ...
... ... ... ... ...
... ... ... ... ...

000532 RENT DSECT
... ... ... ... ...
... ... ... ... ...
... ... ... ... ...
000584 WORK DS 0D
000585 ENQ ENQ (*-*,*-*,E,52,SYSTEMS),RET=USE,MF=L
000586 ENQ2 ENQ (*-*,*-*,E,44,SYSTEMS),MF=L
000587 ENQRSV RESERVE (*-*,*-*,E,44,SYSTEMS),UCB=*-*,MF=L
000588 DEQ DEQ (*-*,*-*,52,SYSTEMS),MF=L
000589 DEQ2 DEQ (*-*,*-*,44,SYSTEMS),MF=L
000590 DEQRSV DEQ (*-*,*-*,44,SYSTEMS),MF=L
000591 PDSDCB DCB DSORG=PO,MACRF=(R),DDNAME=*-*,RECFM=U,EXLST=*-*
000592 PD2DCB DCB DSORG=PO,MACRF=(W),DDNAME=*-*
000593 PD3DCB DCB DSORG=PO,MACRF=(R),DDNAME=*-*
000594 OPENLST OPEN (*-*,(INPUT)),MF=L
000595 OPENLS2 OPEN (*-*,(OUTPUT)),MF=L
000596 CLOSLST CLOSE (*-*),MF=L
000597 DECBR READ DECB1,SF,*-*,*-*,*-*,MF=L
000598 DECBW WRITE DECB2,SF,*-*,*-*,*-*,MF=L
... ... ... ... ...
... ... ... ... ...
... ... ... ... ...
000626 DS 0D
000627 WORKL EQU *-WORK
000628 RENTL EQU *-RENT
... ... ... ... ...
... ... ... ... ...
... ... ... ... ...
000484 DATA DS 0D
000485 ENQ (*-*,*-*,E,52,SYSTEMS),RET=USE,MF=L
000486 ENQ (*-*,*-*,E,44,SYSTEMS),MF=L
000487 RESERVE (*-*,*-*,E,44,SYSTEMS),UCB=*-*,LOC=ANY,MF=L
000488 DEQ (*-*,*-*,52,SYSTEMS),MF=L
000489 DEQ (*-*,*-*,44,SYSTEMS),MF=L
000490 DEQ (*-*,*-*,44,SYSTEMS),MF=L
000491 DCB DSORG=PO,MACRF=(R),DDNAME=*-*,RECFM=U,EXLST=*-*
000492 DCB DSORG=PO,MACRF=(W),DDNAME=*-*
000493 DCB DSORG=PO,MACRF=(R),DDNAME=*-*
000494 OPEN (*-*,(INPUT)),MF=L
000495 OPEN (*-*,(OUTPUT)),MF=L
000496 CLOSE (*-*),MF=L
000497 READ ZZZZ1,SF,*-*,*-*,*-*,MF=L
000498 WRITE ZZZZ2,SF,*-*,*-*,*-*,MF=L
... ... ... ... ...
... ... ... ... ...
... ... ... ... ...
000516 DS 0D
000517 DATAL EQU *-DATA

output ( print gen to show that ... )

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COMMAND INPUT ===> SCROLL ===> CSR
1149 OPEN (*-*,(INPUT)),MF=L
000A64 1150+ DC 0F'0'
000A64 80 1151+ DC AL1(128)
000A65 000000 1152+ DC AL3(*-*)

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