The transport providers are specified with the SUBFILESYSTYPE statements in BPXPRMxx or specified with the SETOMVS command. The default transport provider is one of the following:

• The transport provider specified as the default on the SUBFILESYSTYPE statement in BPXPRMxx.
• If DEFAULT was not specified, the transport provider from the first SUBFILESYSTYPE statement will become the default transport provider while it is active.
• If DEFAULT was not specified, the first SUBFILESYSTYPE transport provider specified is not active, and no other stacks are active, then the first transport provider activated becomes the default. The selection of default transport providers can become unpredictable if stacks are stopped and restarted while the specified default transport provider and the first SUBFILESYSTYPE transport provider are inactive.