the following from the 'code' book for db2/zos. The softcopy of such book is available on line. You better have such document handy for your work.
Explanation: A table space or index space cannot be accessed because DB2 is unable to create the referenced buffer pool. The referenced buffer pool size was zero, which indicates to DB2 that this buffer pool should not be activated. DB2 message DSNB602I was issued to inform the operator of the error. This reason code and the table space or index space name are recorded in the cursor table (CT) and made available to the user in the SQLCA.
This abend reason code is issued by the following CSECTs: DSNB1OPP DSNB1OPS
System action: An SQLCODE -904 (resource not available) is returned to the user. The SVC dump and the SYS1.LOGREC recording are not requested.
System programmer response: Analyze the virtual storage content of the ssnmDBM1 address space to determine further action. If appropriate, use the ALTER TABLESPACE or ALTER INDEX statement to modify the affected table space or index to indicate a usable buffer pool. To determine a usable buffer pool, use the DISPLAY BUFFERPOOL command. If necessary, use the ALTER BUFFERPOOL command to activate the failing buffer pool by setting its VPSIZE to a nonzero value.