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Specifies the Db2® message libraries for the Db2 subsystem defined by SSID.

You only need to specify a value for DB2MLIB if the libraries have not been allocated prior to starting ZDT/Db2. You can do this in several ways, for example, in the TSO logon procedure as JCL statements, or in an initialization clist or exec run as part of the TSO logon procedure, or in a clist or exec executed prior to the initialization of ZDT/Db2.