This Knowledge Document explains the meaning of message SSM0-28 and what actions should be taken.
Message SSM0-28 is generated and written to the Browse File when a JCL member is too large to be sent to a SUBMIT Data Set. If you receive this message, the associated job will be flagged in CA 7 Edition with a JCL ERROR. If this is encountered frequently for more than a single job you should consider increasing the size of the SUBMIT DATA SET. For a single job with this error, it is recommended that the job's JCL be broken up into smaller jobs or execute the majority of the job's JCL from a PROC.