Does load balancer F5 support CasC (Configuration as Code)?
Yes, F5's do support Configuration as Code. Historically, F5 has made an appliance to manage Configuration as Code called "Enterprise Manager" which pragmatically managed client endpoint F5s (LTMs, etc) using the iControl XML API. 

They rather quickly discovered this management appliance was terrible and added a more robust REST API to the client appliances for managing devices (LTMs, etc.; also branded as iControl) which is much easier to use and more flexible and then began building a replacement for the Enterprise Manager branded BIG-IQ.

The point being, you can manage that same API using this REST interface. See their tutorial on DevCentral. Usually, you can find the exact REST syntax and calls on the DevCentral site on a per-version basis like this one for TMOS 12.1.0.

Generally speaking, it is NOT recommended that you use an SCF (Single Configuration File) pretty much ever for a couple of reasons. First, it lacks any supporting files, such as certificates and keys for your SSL profiles or scripted (so-called "external" health monitors), etc. Secondly, it plays poorly if  you use partitioning, as partitions are spread over several files in a foldered structure. These don't consolidate well into an SCF file. You would actually be better off to write TMOS scripts. One of the reasons F5 switched from the bigpipe command to the TMOS shell is that it could be scripted where bigpipe could not be easily scripted. But again, the REST API is preferred. SCFs are really a legacy of version 9 of TMOS and haven't aged well and work poorly in version 12. A significant reason for this is due to the changes in the HA peering between V10 and V11 when they changed to a clustered architecture. It really wreaked havoc on the usability of the SCFs. 

Puppet actually has a module for managing F5s if you use this configuration management tool and salt has a runner for it - both using the REST API if you use either of these configuration management tools.