dbs/db4/install_no_cmtctl is a SAP Parameter attribute which is used to control Switch off commitment control for installation information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
'ON' means that commit control is deactivated during the installation of
the SAP system.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.