This is part of the larger task of customizing your z/OS environment.
When you customize your first broker, you need to create a JCL member, which defines the STEPLIB for the corequisite libraries (DB2, WebSphere MQ, and Language Environment®).
All brokers and User Name Servers can use the same member name. If you want to use a different member name (for example, if you want to use different DB2 libraries), create a new member with the different libraries in it, and override the member name at startup. When the new libraries are working properly, you can change the default STEPLIB member to reflect the new libraries. If you need to switch back to the old member name, specify the old name when you start the broker or User Name Server. See Creating the STEPLIB_NAME member for a broker for further information.