From your SYSTSPRT dump above I can tell you are executing the step using IKJEFT01 which is setting up a TSO environment for execution of your loadmodule.
Loadmodules accessing DB2 from TSO should be linked with the DSNELI or DSNALI attachment module. IMS and CICS interfaces provides other call attachments for the DB2 interface. Source: DB2 (OS390 - z/OS) Application Programming and SQL Guide
If your problem was solved without changing the loadmodule you have probably changed the runtime environment to be consistent with the loadmodule.