History/Common JCL
Many of these utilities were designed by IBM users, through the group SHARE, and then modified or extended by IBM from versions originally written by a user.
These utilities are usually invoked via Job Control Language (JCL). They tend to use common JCL DD identifiers for their data sets:
- SYSIN — input file for the 'commands' for the utility. Often set to DUMMY if the default action is desired.
- SYSUT1 — input file.
- SYSUT2 — output file.
- SYSUT3 — work (spill) file for input (SYSUT1) (often not used).
- SYSUT4 — work (spill) file for output (SYSUT2) (often not used).
- SYSPRINT — output file for printed output from the utility.
- SYSOUT — output file for messages from the utility.
- SYSUDUMP — output file for a system 'dump' if the program fails.
Read more about this topic: IBM Mainframe Utility Programs
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