This can not be considered as a blog. But however, I wanted to record this somewhere so that it gets picked up by search engines and provides a useful clue to a developer struggling with setting up IBM DB2 CLI (TYPE 2) JDBC XA Connection pool.
Scenario:
Setting up an XA Connection pool with "COM.ibm.db2.jdbc.DB2XADataSource"
Database server on remote host. You have IBM DB2 client installed.

Exception:
DB2 DSRA8100E: Unable to get a XAConnection from the DataSource
Root Exception:
[IBM][CLI Driver] SQL1032N No start database manager command was issued. SQLSTATE=57019

If you got this error, got to your command prompt and issue "DB2START" command.
This is a hidden action associated with CLI drivers to work. Hm!