For example I have two users A,B and a function a.func1().

Is any way there to call func1() from user B without mentioning the schema a.func1() ?

Well no, at some point DB2 needs the "a" to find the real function. But I presume what you're trying to do is enable B to invoke the function without having to code a.func1. Some ways you could try:
- create function b.func1 source a.func1
- select current path concat ',A' into :somewhere from sysibm.sysdummy1
set current path = :somewhere

James Campbell