Using the GLBL control statement

The GLBL statement gives you the flexibility to specify these libraries globally, once for all tasks in the batch job. The library names coded on the GLBL statement override any names provided with DD statements in the JCL, but library names coded on the other control statements (XREF, MAP, REPORT, and so on) override the names coded on the GLBL statement. Use of the GLBL statement is entirely optional. You can provide more than one GLBL statement per job step. Each GLBL statement overrides the previously defined libraries and adds to the list of library definitions.