Neo4j DB Stops unknowingly

Neo4j Graph Platform Installation
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I have installed neo4j 4.3.3 in 4GB RAM server. I had given memory allocations as suggested by neo4j-admin memrec .My DB Size nearly 1 GB .There are some miniservices are running in the server
I had given 1900m for heap and 512m for page cache as suggested .But still db stops daily a time unknowingly .I had gone through debug.log No evidence of exceptions or errors present

It has only below statements regarding checkpointing and pruning

021-09-23 11:15:41.618+0000 INFO [o.n.k.i.t.l.c.CheckPointerImpl] [neo4j/86229253] Checkpoint triggered by "Scheduled checkpoint for every 15 minutes threshold" @ txId: 622 checkpoint completed in 37ms
2021-09-23 11:15:41.623+0000 INFO [o.n.k.i.t.l.p.LogPruningImpl] [neo4j/86229253] No log version pruned. The strategy used was '1 days'.
2021-09-23 11:30:41.644+0000 INFO [o.n.k.i.t.l.c.CheckPointerImpl] [neo4j/86229253] Checkpoint triggered by "Scheduled checkpoint for every 15 minutes threshold" @ txId: 624 checkpoint started...
2021-09-23 11:30:41.666+0000 INFO [o.n.k.i.t.l.c.CheckPointerImpl] [neo4j/86229253] Checkpoint triggered by "Scheduled checkpoint for every 15 minutes threshold" @ txId: 624 checkpoint completed in 21ms
2021-09-23 11:30:41.668+0000 INFO [o.n.k.i.t.l.p.LogPruningImpl] [neo4j/86229253] No log version pruned. The strategy used was '1 days'.

My Questions are

  1. Why does the DB Stops?
    2)Does the log pruning induces the db to stop
  2. if 4GB is so low for 1GB data DB how much the RAM Size should be and how much the HEAP,PAGE CACHE Size should be??

Thanks in advance