Does the Xmanager started task need to be up and running before the Database Management for Db2 for z/OS Post Installation steps are executed?
Yes, Xmanager must be running in order to complete the steps for the Db2 catalog customization tasks.
Information and started task information can be found/created in the Database Management for DB2 for z/OS Post Install.
How to get more information on installing and executing Xmanager:
You will then be brought to the PXM Customization Menu. Option 1 contains Customization Information and Option 2 will help Prepare the Xmanager Started Task Procedure.