Digital information is transferred between an application that processes a plurality of on-line transactions executed on the mainframe computer and a file system of an operating system. A programmable processor identifies the data held in memory under control of the application. The programmable processor calls a first routine to associate a portion of the data with a container of the application and calls a second routine to dynamically allocate a file of the file system. The programmable processor opens the file of the file system and calls an input/output routine of the operating system to transfer the data associated with the container to the file of the file system.