fort.18 and fort.19 file size

I am running few test calculations at MRCCSDT level. I realized that, with each amplitude iteration, size of fort.18 and fort.19 file increase. Is there anyway to circumvent this problem? I also noted down, to restart the job, perhaps, I do not need these files. Even I delete these files in junk folder and restart the job , job is restarting. May somebody can enlighten me about utilities of these files (fort.18 and fort.19)

The DIIS parameter and error vectors are stored in these files. In each iteration a vector of length corresponding to the number of cluster amplitudes is saved to both files. Unfortunately it cannot be avoided, but these files are not needed for restart.