For customers new to z/OS, understanding how you can accomplish even easy duties could be a problem. Creating and copying recordsdata, defining z/OS-unique objects reminiscent of Era Knowledge Teams (GDGs) and VSAM datasets, and simply getting dataset info in z/OS programs is totally different. Thankfully, there’s a ‘Swiss-Military knife’ that may carry out all these duties and rather more. IDCAMS, the Entry Technique Providers utility, is among the most essential and extensively used functions in any z/OS system. IDCAMS is utilized by each functions and programs programmers to carry out duties starting from file creation and reporting to managing catalogs and tape libraries. IDCAMS amazingly wide selection of operate means there’s virtually nothing you’ll be able to’t do with it – let’s check out the way it works and a number of the extra frequent duties we are able to carry out.
JCL and Management Statements
The Job Management Language (JCL) required to execute IDCAMS is remarkably easy. Moreover the EXEC PGM=IDCAMS assertion, all that’s normally required is a SYSPRINT dataset for the output and a SYSIN dataset for the management statements. Most different datasets, if they’re wanted, could be referenced within the management statements or dynamically allotted. About thirty totally different management statements enable the person to carry out virtually any dataset or catalog-related z/OS operate. The ‘modal’ instructions (IF-THEN, DO-END, SET, and so forth.,) management the circulate of operations if a couple of operate is to be carried out, however it’s the ‘purposeful’ instructions (DEFINE, ALTER, LISTCAT, and so forth), that do the work.
Frequent Duties – Creating VSAM Clusters and Extra
The DEFINE command, used to create datasets or catalog entries, is probably the most generally used of the purposeful instructions. DEFINE has various variations, relying upon whether or not one is making a VSAM cluster (i.e., a VSAM dataset, most likely the most typical use) or one thing else, reminiscent of an alias, usercatalog, GDG, or non-VSAM catalog entry. Quite a few parameters on the DEFINE command specify all the many detailed traits of the cluster or different entity that’s being outlined. For a posh dataset reminiscent of a VSAM key-sequenced cluster with alternate indexes and pathnames, extra instructions (DEFINE AIX, DEFINE PATH) comply with the DEFINE CLUSTER command used to create the bottom VSAM dataset and are used to create the extra elements of the cluster, reminiscent of indexes and pathnames. Finally, for many VSAM DEFINEs in addition to many different features, reminiscent of LISTCAT, IDCAMS invokes SVC 26 to do the precise work required.
Along with VSAM clusters, the DEFINE command can be utilized to create many different objects, utilizing variations reminiscent of DEFINE GDG (to create era datasets), DEFINE ALIAS (to create alternate names for datasets or qualifiers), and DEFINE USERCATALOG (to create catalogs). DEFINE NONVSAM can be utilized to create non-VSAM catalog entries, however the creation of precise non-VSAM datasets (versus simply catalog entries) is completed with the ALLOCATE command, which features in the identical approach because the similar TSO command.
After Creation – Loading, Altering, Copying
As soon as a dataset or a catalog entry (reminiscent of a GDG base) is outlined, the ALTER command permits IDCAMS to alter virtually any attribute of the entity if wanted. A dataset, after all, is barely helpful if it truly incorporates knowledge – the IDCAMS REPRO command is due to this fact used to load VSAM clusters from sequential datasets (or different VSAM clusters). REPRO can be typically to repeat knowledge from one dataset to a different. Parameters on the REPRO command specify if data ought to be skipped, encrypted/decrypted, and whether or not present recordsdata or data could be overlaid with new knowledge (REPLACE and REUSE). REPRO can be utilized by system programmers for such duties as merging person catalogs. Determine 1 exhibits a typical IDCAMS job that could be used to create a keyed VSAM cluster, load it with knowledge through REPRO, and replace the alternate index through the BLDINDEX command.
Eradicating Knowledge
Datasets normally ‘dwell’ on disk for under so lengthy earlier than storage administration utilities reminiscent of DFSMShsm or FDRABR robotically delete them. The IDCAMS DELETE command, nevertheless, can be utilized to intentionally take away nearly any kind of dataset or catalog entry. Operands reminiscent of PURGE and FORCE can be utilized to delete unexpired datasets or non-empty GDGs. The MASK operand, which permits mass deletion of huge numbers of like-named datasets, could be significantly helpful. Determine 2 exhibits two makes use of of DELETE – eradicating and erasing all datasets with a specified naming conference, and eradicating an ‘orphan’ VVR for a VSAM cluster which occurs to be incorrectly uncatalogued.
Displaying Catalog Entries
By far the oldest, commonest, and important use of IDCAMS is the LISTCAT command. LISTCAT is used to show the contents of catalog entries based mostly on their identify, and maybe kind, reminiscent of CLUSTER, NONVSAM, or USERCATALOG. In contrast to the DELETE command, there isn’t any MASK choice. Catalog entities to be listed are specified by the ENTRIES or LEVEL parameters, which permit for a sure restricted quantity of masking through the ‘*’ or ‘%’ characters. The format of the LISTCAT output is fastened, and varies relying upon the kind of entries being listed. If the LISTCAT command occurs to pick out entries from a number of catalogs, they seem in catalog order slightly than in alphabetical order. As a result of LISTCAT’s choice filtering is restricted and the output can’t be modified (and sometimes consists of extra info than could be vital), it’s frequent to make use of the OUTFILE parameter to direct the output from LISTCAT to a DD assertion. From there, the fixed-format output can then be parsed and processed by a extra versatile REXX exec. Determine 3 exhibits the usage of LISTCAT to show a subset of the tape quantity entries for a specific tape library, with the output directed to a dataset.
The z/OS DFSMS Entry Technique Providers Instructions guide (SC23-6846) describes every of the IDCAMS instructions intimately, together with JCL examples, pattern output, and an outline of the interface that can be utilized to invoke IDCAMS from a program.
Nonetheless Extra IDCAMS Features
There are various extra IDCAMS features in addition to these listed above. Notably helpful instructions for debugging are PRINT, which shows the contents of VSAM or non-VSAM datasets or catalogs, and the EXAMINE and VERIFY instructions. EXAMINE can be utilized to seek out issues with the construction of complicated multi-component key-sequenced or relative file VSAM datasets (KSDS or VRRDS). VERIFY is run to detect and repair VSAM end-of-file errors which might come up if errors happen when a VSAM dataset is closed.
There’s additionally a plethora of specialised IDCAMS features used principally by storage directors and system programmers. These embrace operations reminiscent of IMPORT, EXPORT, and RECOVER instructions for managing catalogs, and instructions associated to VSAM record-level sharing (RLS), reminiscent of SETCACHE and LISTDATA. One IDCAMS command that deserves particular point out is DCOLLECT, which produces system-level, dataset-level and quantity degree data that may be processed to supply detailed reviews on the DFSMS storage surroundings.
Conclusion
To explain all the things that may be completed with IDCAMS would require a complete e-book. Thankfully, there may be such a e-book. The z/OS DFSMS Entry Technique Providers Instructions guide (SC23-6846) describes every of the IDCAMS instructions intimately, together with JCL examples, pattern output, and an outline of the interface that can be utilized to invoke IDCAMS from a program. The guide, vital in each z/OS programmer’s toolkit, could be discovered at right here.
IDCAMS is accessible in each z/OS set up as it’s a part of DFSMS, the storage administration part of the working system. It’s an important instrument for each software and system programmers and whether or not they’re new to z/OS or grizzled veterans.
