The usual culprit is when REXXON is coded incorrectly, in an application, where an ALLOCX statement has been issued (usually in a loop after the JOBONCSF statement) with no corresponding FREEX command issued. If there are thousands of jobs in the CSF queue, the dataset will be allocated that many times - filling up the table.
Solution: Add the needed FREEX code in the APPL and recycle ESP to free the allocated datasets.
ESP528E ERROR OCCURRED PROCESSING EVENT <event name> ESP2720E UNABLE TO ALLOCATE <jcl name>, S99 ERROR CODE X'0238', INFO CODE X'0000' ESP1800I ABOVE ERROR OCCURRED ON FOLLOWING STATEMENT ESP1007I JCLLIB '<jcl name>'
This Frequently Asked Question applies to all supported releases of ESP Workload Manager beginning with 5.3.