Member
One named item inside a partitioned dataset, such as a single program, job or copybook within a library.
Also written PDS member
A member is an individual entry in a partitioned dataset. Its name can be up to eight characters, uppercase, starting with a letter, and it holds its own content independently of the other members around it.
You refer to a member by putting its name in brackets after the dataset name. That notation appears everywhere: in JCL when pointing a job at a procedure, in ISPF when opening a file to edit, in documentation when telling someone where code lives.
Because names are capped at eight characters, mainframe naming conventions are terse and systematic. Sites use prefixes and suffixes to encode what a member is, so a library of two hundred members is still navigable.
Working with them is straightforward. ISPF gives you a member list you can browse, edit, rename, copy and delete from, and most of what you do while learning happens in that list: writing JCL in one member, COBOL in another, and running one against the other.
Related terms
- Partitioned datasetA dataset that works like a library or folder, holding many separately named members inside one dataset.
- PDSEThe modern version of a partitioned dataset, which reclaims space automatically and removes the old size limits.
- ISPF editorThe full-screen text editor used to write and change JCL, COBOL, REXX and anything else held in a dataset.
- CopybookA shared block of COBOL declarations kept in a library and included into programs, so a record layout is defined once.
- JCLJob Control Language: the language used to tell the mainframe what programs to run, in what order, and with what files.