You must use the EDG_EXIT300 installation exit to dynamically set media information for volumes that have a media information name (MEDINF operand) other than IBM. If you do not use the EDG_EXIT300 installation exit, only the volumes with an IBM MEDINF name are maintained dynamically. Use the EDG_EXIT300 installation exit to supply media information for a specific volume for non-IBM media using the vendor API. The exit is called during O/C/EOV processing if the installation-defined media information for this volume is not IBM, and you have MEDINF definitions.