Abstract: Methods, and computer program product, the computer program product comprising program instructions implementing: a cloud agent module executed by the mainframe computer for communicating with the cloud storage; one or more first routines implementing low level I/O control events of the mainframe computer, including at least mount and unmount routines, said first routines substituting one or more OS routines executed by the mainframe computer; a SAM EOB routine for calling the cloud agent module to transmit or retrieve data from the cloud storage, the SAM EOB routine substituting an OS routine; and one or more exit routines, called for Open, Close and End of Volume related events, said exit routines sending notifications to the cloud agent module.

Abstract: Methods, and computer program product, the computer program product comprising program instructions implementing: a cloud agent module executed by the mainframe computer for communicating with the cloud storage; one or more first routines implementing low level I/O control events of the mainframe computer, including at least mount and unmount routines, said first routines substituting one or more OS routines executed by the mainframe computer; a SAM EOB routine for calling the cloud agent module to transmit or retrieve data from the cloud storage, the SAM EOB routine substituting an OS routine; and one or more exit routines, called for Open, Close and End of Volume related events, said exit routines sending notifications to the cloud agent module.

Abstract: Methods, and computer program product for writing data sets to and from cloud storage for legacy mainframe applications. A call to a mount request issued by the operating system is intercepted. An exit call to prepare for dataset write is received from an OS open routine. At least one call to a Basic Sequential Access Method (BSAM) End of Block (EOB) write routine is intercepted. Subject to the at least one call to the BSAM EOB routine being associated with cloud storage, data chunks are sent in an asynchronous manner to cloud storage. A second exit call for finalizing writing of the data chunks to the cloud storage is received. A call to an unmount request is intercepted. As a result, data is written directly from the mainframe to the cloud storage without intermediate storage.