TSO is a user interactive access facility in OS/390 or z/OS system for common purposes. Using TSO, people can interact to the system in either follow native MVS or Unix style, which can be switched any time. Users might be general users, operators, programmers, analysts, engineers, administrators or managers, who need different access authorization. When more facilities are needed, higher authority is required and more data and files need to be accessed too. This will increase I/O table and affect data searching time... and of course, will affect to the response time, at least for appropriate users. Hence, ideally each user should keep minimum file configuration. Use only the most common files, unless certain function is needed. This policy is very hard to do, since I/O table is not designed to be changed during logging session. Administrator usually provides various logon procedures, so when someone needs to change file configuration, logoff and relogin using different logon procedure.
You can actually change them interactively using FREE and ALLOCATE commands, which are TSO standard utilities. For example, when you want to concatenate dataset MY.LIB to your existing FILE1 file which consist of LOCAL.LIB followed by SYS1.LIB. You need to do the following steps:
The problem is, you must remember the number of datasets included in the file construction and their order before you issue FREE command. Issuing ALLOCATE command also not very easy. Imagine if the file construction consists of tens of datasets and all with long names.
CCAT©was developed to avoid that ridiculous thing. It was designed to change TSO I/O table any time interactively on the fly. With CCAT, users can concatenate and/or deconcatenate any dataset of any file at any time they want. For the above example, you can do it simply, just one step, issue:
ccat file(FILE1) dataset(MY.LIB)
Dataset MY.LIB will automatically concatenated on top of original FILE1 construction without releasing any dataset.
CCAT can also be used to release a dataset from a file construction, and to display list of datasets included in a file construction.
|Environment||TSO/E of OS/390 or MVS/ESA|
|Note||This product is also distributed by CBTTAPE in TSO XMIT|