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![]() DISP parameter z/OS MVS JCL Reference SA23-1385-00 |
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Parameter Type Keyword, optional Purpose Use the DISP parameter to describe the status of a data set to the system and tell the system what to do with the data set after termination of the step or job. You can specify one disposition for normal termination and another for abnormal termination. Note that if an abend occurs within a step, the step itself may terminate normally or abnormally, depending on whether an ESTAE (or ESPIE routine) intercepts the abend and requests that processing continue. Normal termination of a step is indicated by the presence of message IEF142I; abnormal termination of a step is indicated by the presence of message IEF472I. Note: Disposition of the data set is
controlled solely by the DISP parameter; disposition of the volume(s) on which the data set resides is a function
of the volume status when the volume is demounted. If the UNIT parameter
specifies a device, such as a printer or telecommunications device,
that does not involve a data set, do not code the DISP parameter.
If the system obtains unit and volume information for an OLD, MOD, or SHR status, the data set is treated as if it exists, whether or not it is physically on the device. When any step of a job requests exclusive control of a data set,
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If a dynamic allocation requests exclusive control
of a data set then all subsequent DISP=SHR JCL references to that
data set within that job will be upgraded to exclusive control. The
job will retain exclusive control of that data set until the end of
the last step of that job which references that data set in its JCL.
For example:
Before the start of STEP1, the job will request shared
control of data set A.B.C. In STEP2, the DELETE/DEFINE of data set
A.B.C will cause the shared control from STEP1 to be upgraded to exclusive
control. In STEP3, control of data set A.B.C will remain exclusive,
since it is not possible to downgrade an ENQ from EXCL to SHR DISP and ENQ: Before starting the first step of a job, the initiator requests control of all of the data sets in that job by issuing an ENQ for each of them, using the value specified for DISP to determine the kind of ENQ issued. The initiator issues the ENQ for each data set at the highest level required for that data set by any step of the job. For example, if all steps of the job request shared control of a specific data set (DISP=SHR) then the ENQ for that data set is requested as SHR. If, on the other hand, any step of the job requests exclusive control of a specific data set (DISP=NEW, DISP=MOD, or DISP=OLD), then the ENQ for that data set is requested EXCL.
DISP and ENQ for generation
data sets: The way the initator issues an ENQ to control generation
data sets can be different than with other data sets. The initiator
only issues the ENQ for the GDG base name for a generation data set
that is referenced by either:
Note that the initiator does not issue an ENQ for the GDG base name for a generation data set that is referenced by its absolute GDG name. Instead it issues an ENQ for that specific G0000V00 data set name. References For information about tape data set processing, see z/OS DFSMS Using Magnetic Tapes. ![]() ![]() ![]() |
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