Firmware versions 3.60 and 3.65 support Enso , a plugin that keeps your console jailbroken permanently when you reboot. 3.74 requires you to re-run the exploit tool frequently.
You can find the official update file on the PS Vita System Software Support page . : PSVUPDAT.PUP Update Size : Approximately 150 MB. Impact on Homebrew & Jailbreaking ps vita 374 firmware link