Ffmpeg by cuda publish rtsp stream error(CUDA_ERROR_OUT_OF_MEMORY:out of memory)

I have a RTX5000 Graphics card,I want 100 rtsp streams(4CIF) to CIF,but when I only can Translations of 58 streams .when I try Translations of 59 streams。ffmpeg reback err:
CUDA_ERROR_OUT_OF_MEMORY:out of memory。why?image