Pocketmine-MPのファイルにあるPocketmine.yml を開いて下さい

# Main configuration file for PocketMine-MP
# These settings are the ones that cannot be included in server.properties
# Some of these settings are safe, others can break your server if modified incorrectly
# New settings/defaults won't appear automatically on this file when upgrading.

 #Three-letter language code for server-side localization
 #Check your language code on https://en.wikipedia.org/wiki/List_of_ISO_639-2_codes
 language: "eng"
 #Whether to send all strings translated to server locale or let the device handle them
 force-language: false
 shutdown-message: "Server closed"
 #Allow listing plugins via Query
 query-plugins: true
 #Show a console message when a plugin uses deprecated API methods
 deprecated-verbose: true
 #Enable plugin and core profiling by default
 enable-profiling: false
 #Will only add results when tick measurement is below or equal to given value (default 20)
 profile-report-trigger: 20
 #Number of AsyncTask workers.
 #Used for plugin asynchronous tasks, world generation, compression and web communication.
 #Set this approximately to your number of cores.
 #If set to auto, it'll try to detect the number of cores (or use 2)
 async-workers: auto

 #Global soft memory limit in megabytes. Set to 0 to disable
 #This will trigger low-memory-triggers and fire an event to free memory when the usage goes over this
 global-limit: 512  //ここで変更できます

 #Main thread soft memory limit in megabytes. Set to 0 to disable
 #This will trigger low-memory-triggers and fire an event to free memory when the usage goes over this
 main-limit: 320

 #Period in ticks to check memory (default 1 second)
 check-rate: 20

 #Continue firing low-memory-triggers and event while on low memory
 continuous-trigger: true

 #Only if memory.continuous-trigger is enabled. Specifies the rate in memory.check-rate steps (default 30 seconds)
 continuous-trigger-rate: 30

  #Period in ticks to fire the garbage collector manually (default 30 minutes), set to 0 to disable
  #This only affect the main thread. Other threads should fire their own collections
  period: 36000

  #Fire asynchronous tasks to collect garbage from workers
  collect-async-worker: true

  #Trigger on low memory
  low-memory-trigger: true

  #Limit of chunks to load per player, overrides chunk-sending.max-chunks
  trigger-limit: 96

  #Do chunk garbage collection on trigger
  trigger-chunk-collect: true

  #Trigger on low memory
  low-memory-trigger: true

  disable-chunk-cache: true
  low-memory-trigger: true

 #Threshold for batching packets, in bytes. Only these packets will be compressed
 #Set to 0 to compress everything, -1 to disable.
 batch-threshold: 256
 #Compression level used when sending batched packets. Higher = more CPU, less bandwidth usage
 compression-level: 7
 #Use AsyncTasks for compression. Adds half/one tick delay, less CPU load on main thread
 async-compression: false
 #Experimental, only for Windows. Tries to use UPnP to automatically port forward
 upnp-forwarding: false

 #If > 1, it will show debug messages in the console
 level: 1
 #Enables /status, /gc
 commands: false

 #The default format that levels will use when created
 default-format: mcregion
 #If true, converts from a format that is not the default to the default format on load
 #NOTE: This is currently not implemented
 convert-format: false
 #Automatically change levels tick rate to maintain 20 ticks per second
 auto-tick-rate: true
 auto-tick-rate-limit: 20
 #Sets the base tick rate (1 = 20 ticks per second, 2 = 10 ticks per second, etc.)
 base-tick-rate: 1
 #Tick all players each tick even when other settings disallow this.
 always-tick-players: false

 #Amount of chunks sent to players per tick
 per-tick: 4
 #Amount of chunks sent around each player
 max-chunks: 192
 #Amount of chunks that need to be sent before spawning the player
 spawn-threshold: 56
 #Save a serialized copy of the chunk in memory for faster sending
 #Useful in mostly-static worlds where lots of players join at the same time
 cache-chunks: false

 #Max amount of chunks processed each tick
 per-tick: 40
 #Radius of chunks around a player to tick
 tick-radius: 3
 light-updates: false
 clear-tick-list: true

 #Max. amount of chunks in the waiting queue to be generated
 queue-size: 8
 #Max. amount of chunks in the waiting queue to be populated
 population-queue-size: 8

 animal-spawns: 400
 monster-spawns: 1
 autosave: 6000
 cache-cleanup: 900

  monsters: 70
  animals: 15
  water-animals: 5
  ambient: 15

 #Send crash reports for processing
 enabled: true
 send-code: true
 send-settings: true
 send-phpinfo: false
 host: crash.pocketmine.net

 #Sends anonymous statistics for data aggregation, plugin usage tracking
 enabled: true
 host: stats.pocketmine.net

 enabled: true
  warn-console: true
  warn-ops: true
 #Can be development, beta or stable.
 preferred-channel: beta
 #If using a development version, it will suggest changing the channel
 suggest-channels: true
 host: www.pocketmine.net

 #showtheversion: version
 #savestop: [save-all, stop]

 #These settings will override the generator set in server.properties and allows loading multiple levels
 # seed: 404
 # generator: FLAT:2;7,59x1,3x3,2;1;decoration(treecount=80 grasscount=45)