How to get the ZOS DB2 Version in mainframe?

Go to QMF or Spufi.

Execute the below query.

SELECT GETVARIABLE('SYSIBM.VERSION') FROM SYSIBM.SYSDUMMY1

The result would be of format pppvvrrm.

ppp - product string
vv  - Version
rr - Release number
m - Modification level

Example: DSN11015 means DB2 Version 11 in new-function mode.

DSN - DB2 for z/OS
11 - DB2 Verison 11
5 - modification level 5 means New-function mode.