fab library 

The basic protocol described here covers the construction of Fab libraries (naïve libraries) in the phagemid vector, pComb3 (Fig.1). This vector has one important feature is that it contains both origin replication of muticopy E.coli plasmid colE1 and the origin of replication of the filamentous bactriohage f1. Furthermore, pComb3 harbors the gene for enzyme β-lactamase that confers ampicillin resistance to bacteria that contain pComb3 DNA. When you design fab library by phage display, you have two choices: 1. Construct library of HC + κ chain or HC + λ chain; 2. Construct library of HC + κ chain + λ chain after mix κ and λ chain. Select appropriate combination of chains according to your need. The basic protocol flow chart is shown in Fig.2.
https://www.creative-biolabs.com/fab-library-construction-protocol.html