Enable core-dumps in procd

This worked for me by editing the /etc/init.d script:
procd_set_param limits core="unlimited"

example procd script:

#!/bin/sh /etc/rc.common
START=90
STOP=10

# SERVICE_DAEMONIZE=1
# SERVICE_WRITE_PID=1

USE_PROCD=1

start_service() {
        procd_open_instance
        procd_set_param command /usr/bin/myprogram
        procd_set_param respawn
        procd_set_param term_timeout 60
        procd_set_param pidfile /var/run/myprogram.pid # write a pid file on instance start and remove it on stop
        procd_set_param limits core="unlimited"
        procd_close_instance
}