On Sun, 6 Aug 2017 10:34:42 -0700, Sri h Kolusu <skol...@us.ibm.com> wrote:

>> Can somebody shed light on this issue - in simple terms please :) ? 
>
>Theo,
>
>It would be best to avoid concatenation with referback due to the 
>potential problems caused by the system restriction described here in the 
>second bullet:
>
>https://www.ibm.com/support/knowledgecenter/SSLTBW_2.1.0/com.ibm.zos.v2r1.icem100/beaware.htm
>
>Be aware that, in some cases, if a DD statement specifies a data set for 
>output that is extended to a second or subsequent volume, and another DD 
>statement within the same step requests the same data set, only the 
>records on the first volume will be read, and incorrect output will 
>result. 
>
>We always recommend to use one temp data set with disposition MOD . i.e
>
>//TEMP1      DD DSN=&&amp;TEMP1,UNIT=SYSDA,DISP=(MOD
>,PASS),SPACE=(CYL,(X,Y),RLSE)
>
>Copy your datasets into a single dataset with MOD disposition and you will 
>not run into the system restriction.
>
>I am guessing that you are using SPLICE operator to find the matching 
>records between 2 files IN1 and IN2. Please note that JOINKEYS is much 
>more efficient technique and it can even handle MANY to MANY match which 
>SPLICE operator cannot handle.
>
>Since I don't have your entire TOOLIN Cards I cannot rewrite your JCL. If 
>you can send your TOOLIN statements then I can optimize the job or convert 
>it to use JOINKEYS.
>
>Further if you have any questions please let me know
>
>>>>Since I do not know this tool you are using or what it will do, it 
>might be possible to use something like SORT to do what you want.
>
>Lizette,
>
>The Job is indeed using ICETOOL
>
>
>Thanks,
>Kolusu
>DFSORT Development
>IBM Corporation
>

You're right.
Because the CONCAT DDs are referencing new TEMP1 and TEMP2 in the same step - 
they will not see any additional volume that TEMP1 and TEMP2 will overflow 
into. The updated volume information will not be available to the CONCAT DDs. 
Hence the S637-BC, which says "The last known volume for the data set could not 
be located while reading a multivolume DASD data set" for the CONCAT DD.
This is stated in the JCL Ref. manual, discussing the VOL=REF=*.ddname 
parameter (same step).

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