DB updates with ROracle - ORA-01000

I have an R script that makes an ROracle connection to a DB and pulls data.. analyzes and then updates approx 7,000 records.

I have two functions defined in my script that look like this:

       # Create the updateTC function
        updateTC <- function(dfrm) {
                with(dfrm, {
                updateDB(paste("update SIMETRA.RTA_MARKET_STATS set CLOSEST_LOC_TRAVEL_COEFFICIENT = '",format(GEOGRAPHIC_COEFFICIENT, scientific=FALSE, digits=6),"' where RTA_MARKET_STATS_ID = '",MSID,"'", sep = ""))
                })
        }

        # Create the updateDB function
        updateDB <- function(stmt) {
                for (update in stmt) {
                        res <- dbSendQuery(conn, update)
                        res <- dbCommit(conn)
                        summary(drv)
                }
        }

and I call it like so (cr is a dataframe with my results):

        # Update the DB with the new geographic coefficients
        updateTC(cr)
        res <- dbCommit(conn)

You can tell I wrote this code while still familiarizing myself with vector-based functions, but I still don't know the most efficient way to get the fields updated properly.  Still, when I had this same code using the RJDBC driver, I had no issues with cursors (I switched for other reasons).  But now I immediately get an ORA-01000 from the database, which is "Maximum open cursors exceeded"...

Thoughts?  I don't think I should increase the maximum cursors on the DB to > 7,000.  I put in the dbCommit after the update in an attempt to release cursors, but I feel I am missing something important.

Any assistance is greatly appreciated,

David