IEFBR14 UTILITY PDF

It is a placeholder that returns the exit status zero, similar to the true command on UNIX-like systems. IEFBR14 was created because while DD statements can create or delete files easily, they cannot do so without a program to be run due to a certain peculiarity of the Job Management system, which always requires that the Initiator actually execute a program, even if that program is effectively a null statement. Thus a very simple do-nothing program was needed to fill that role. A secondary reason to run IEFBR14 was to unmount devices usually tapes or disks that had been left mounted from a previous job, perhaps because of an error in that job's JCL or because the job ended in error.

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It is a placeholder that returns the exit status zero, similar to the true command on UNIX-like systems.

IEFBR14 was created because while DD statements can create or delete files easily, they cannot do so without a program to be run due to a certain peculiarity of the Job Management system, which always requires that the Initiator actually execute a program, even if that program is effectively a null statement.

Thus a very simple do-nothing program was needed to fill that role. A secondary reason to run IEFBR14 was to unmount devices usually tapes or disks that had been left mounted from a previous job, perhaps because of an error in that job's JCL or because the job ended in error.

In either event, the system operators would often need to demount the devices, and a started task — DEALLOC — was often provided for this purpose. Also, all such started tasks must be a single jobstep as the "Started Task Control" STC module within the Job Management component of the operating system only accepts single-step jobs, and it fails all multi-step jobs, without exception. The "IEF" derives from a convention on mainframe computers that programs supplied by IBM were grouped together by function or creator and that each group shared a three-letter prefix.

As explained below, "BR 14" was the essential function of the program, to simply return to the operating system. As explained further in "Usage" below, the name "BR14" comes from the IBM assembler-language instruction " B ranch to the address in R egister 14 ", which by convention is used to "return from a subroutine ".

BR is a pseudo instruction for BCR But, initially IEFBR14 was not coded with these characteristics in mind, as IEFBR14 was initially used as a dummy control section, one which simply returned to the caller, not as an executable module. The original version of the program did not alter register 15 at all as its original application was as a placeholder in certain load modules which were generated during Sysgen system generation , not as an executable program, per se. Later, a second instruction was to be added to clear the return code so that it would exit with a determinant status, namely zero.

Initially, programmers were not using all properties of the Job Control Language, anyway, so an indeterminate return code was not a problem. However, subsequently programmers were indeed using these properties, so a determinate status became mandatory. Addison Wesley. From Wikipedia, the free encyclopedia. IBM Corporation.

Retrieved Mike Taylor. Categories : IBM mainframe operating systems. Namespaces Article Talk. Views Read Edit View history. Contribute Help Community portal Recent changes Upload file.

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IEFBR14 JCL Utility Quick Reference

IEFBR14 does nothing but when running this utility other systems services gets invoked which can perform useful tasks like allocating, creating data sets or deleting data sets etc. So this utility allows the steps to execute and it only sets the return code to Zero on a successful execution of the step. Example- Daily or weekly jobs which produces output data sets with a specific name. For next runs of the job, if the generate output data set is not deleted, job gets failed so to avoid this generated data sets must be deleted before the next run. So this utility can be used to delete these generated files. Example to Delete a Dataset:.

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