PHP APC配置shm_size

I am about to use PHP APC for the first time but im not sure on the configuration settings.

I am using a apache VPS server with 32GB ram 12-cores, Varnish, and storing static files on Amazon S3.

And running on the server is my php/mysql application.

But would setting apc.shm_size to 1024M be too much? Using 1gb of my 32gb.

Also, would it be a good idea to run a cron-job each day, Eg 5am to clear the cache? so the cache doesnt become fragmented.

Here are my settings:

extension=apc.so
apc.enabled=1
apc.shm_size=1024M
apc.cache_by_default="1"
apc.shm_segments="1"
apc.ttl="7200"
apc.user_ttl="7200"
apc.gc_ttl="1800"
apc.optimization = 0
apc.num_files_hint="1024"
apc.use_request_time = 1
apc.mmap_file_mask="/tmp/apc.XXXXXX"
apc.enable_cli="0"
apc.slam_defense="0"
apc.file_update_protection="2"
apc.max_file_size="1M"
apc.stat="1"
apc.write_lock="1"
apc.report_autofilter="0"
apc.include_once_override="0"
apc.rfc1867="0"
apc.rfc1867_prefix="upload_"
apc.rfc1867_name="APC_UPLOAD_PROGRESS"
apc.rfc1867_freq="0"
apc.localcache="0"
apc.localcache.size="512"
apc.coredump_unmap="0"

And my cron-job which I would use everyday 5am:

<?php
if (in_array(@$_SERVER['REMOTE_ADDR'], array('127.0.0.1', '::1')))
{
  apc_clear_cache();
  apc_clear_cache('user');
  apc_clear_cache('opcode');
  echo json_encode(array('success' => true));
}
else
{
  die('Not c');
}

Thanks in advance,