Of course you looked here, right?
http://publib.boulder.ibm.com/infocenter/zos/v1r9/index.jsp?topic=/com.ibm.zos.r9.ceea900/lemes.htmCEE0813S
Insufficient storage was available to satisfy a get storage (CEECZST) request.
Explanation:
There was not enough free storage available to satisfy a get storage call to CEEGTST or reallocate request call to CEECZST.
Programmer response:
Ensure that the REGION size is sufficient to run the application. Ensure that the size parameter in the get storage request is not an unusually large number. Verify that the storage sizes specified in the HEAP and STACK run-time options are reasonable, given the region size allocated to the application. Verify that you are using storage options that get your storage from above the line, if you can, since you can run out of storage below the line much more easily.
Additionally:
http://www-1.ibm.com/support/docview.wss?rs=2231&context=SS6SG3&dc=DB520&uid=swg21199554&loc=en_US&cs=UTF-8&lang=enCEE0813S Insufficient storage was available to satisfy a get storage - when using FUNCTION UPPER-CASE, etc.
And:
http://www-1.ibm.com/support/docview.wss?uid=swg1PQ39129PQ39129: CEE0813S INSUFFICIENT STORAGE WAS AVAILABLE TO SATISFY A GET STORAGE (CEECZST) REQUEST.