JOBLIB is a private library specifies to the system that where programs named in step EXEC exists for the entire job.
JOBLIB libraries are of type PDS.
Each member in the PDS is a user written program and executable.
The JOBLIB DD statement is used to identify a program library to search first when attempting to locate programs executed during the job execution.
The JOBLIB should be placed in between the JOB Card and first EXEC statement.
//JOBLIB DD DSN=private-library
More than one library can be concatenated on the JOBLIB.
If a STEPLIB DD is specified in a job that also has a JOBLIB, the STEPLIB takes precedence when searching for a program.
JOBLIB should not be coded in in-stream or cataloged procedures.
JOBLIB is used to specify the library where the load resides for the programs which are all executing in the JOB.
This JOBLIB will be used to specify the load library if it is common for more than one program that is coded in the JCL.
JOBLIB statement must be coded after the job card and before the STEPLIB
If any questions on the above, post your queries on Jcl Discussion forum
JCL STEPLIB JCL JCLLIB