configure client ibm_db2 for php
With the help of @mustaccio achieved do as follows: 

First I added the user db2inst1:      


  db2inst1 useradd


Then, I generated the instance (whatever it means) 
              


  /opt/ibm/db2/V10.5/instance/db2icrt db2inst1


Edit the php configuration file (/etc/php.ini) for add the instance: 
     

 extension = / usr/lib64/php/modules/ibm_db2.so 
 ibm_db2.instance_name = db2inst1


Edit the initialization file of the php-fpm service (/etc/init.d/php-fpm), which in my case is the one who runs php, to do the source of the db2profile script under the user running this service each time it starts. 

 #for DB2
 . /opt/ibm/db2/V10.5/cfg/db2profile


And finally restart the service: 


  php-fpm restart service 


Thank you very much for the comments.