IEC707I

Explanation
The open option RDBACK has been specified for a
standard label tape written in compaction mode. If the program is
opening a compacted tape data set with the RDBACK option specified,
performance will be degraded. If the program is not opening a compacted
tape data set with the RDBACK option specified, follow the diagnostic
procedures.
In the message text: dev
Device number.
ser
Volume serial number.
jjj
Job name.
sss
Step name.
dsname
Data set name.

System action
The job step continues processing.

Operator response
Record the indicated information for use of
the volume in conjunction with subsequent requests.
Start a
generalized trace facility (GTF) trace, and re-create the problem.
 Reply to message AHL100A with: TRACE=SYS,USR,SLIP

On
the DD statement for the data set in error, specify: DCB=DIAGNS=TRACE

System programmer response
If the error recurs and the program
is not in error, look at the messages in the job log for more information.
Search problem reporting data bases for a fix for the problem. If
no fix exists, contact the IBM® Support
Center. Provide the JCL, the SYSOUT output, the program listing for
the job, and all printed output and output data sets related to the
problem.

Source
DFSMSdfp