DB2, to check size on C procedures

When defining a procedure like this:

create or replace procedure xxx.name
(in  table_name varchar(6)
,in  key_columns varchar(3000)
)
external name 'lib.so-VERSION!LIBNNN'
language c
parameter style sql
modifies sql data
commit on return no
program type sub;

Do I need to check the size of the input inside the C implementation of the procedure (so that I dont't risk buffer overflows)? ...Is there an error before the C code is invoked? I cannot run my own tests so any help is appreciated!