By default, automatic allocation is inactive after IPLing the system. However, you can add to your COMMNDxx parmlib member the DUMPDS NAME= command, any DUMPDS ADD commands, and the DUMPDS ALLOC=ACTIVE command to activate automatic allocation during IPL.
If you have turned off automatic allocation using ALLOC=INACTIVE, reactivate it by entering the DUMPDS ALLOC=ACTIVE operator command.