IBM z15 replaces the former I/O attached accelerator for DEFLATE, zEnterprise Data Compression (zEDC) Express, with an on-chip accelerator that can be synchronously accessed via an instruction. The integration of this new accelerator in the z/OS software stack has been designed to maintain a consistent user experience for software packages that used the previous technology, while still allowing the enhanced aspects of the new technology to deliver the additional value. Two different access paths for DEFLATE have been created in z/OS to accomplish both goals. For user space programs that utilize the zlib API, z/OS directly executes the instruction synchronously, which avoids overhead and reduces latency. Authorized users continue to utilize existing infrastructure and have the Service Assist Processors (SAP) perform compression in an asynchronous fashion on their behalf. The SAP receives information about the requested task via a thin and efficient communication path to z/OS, invokes the instruction in a well-defined fashion, and returns the result to z/OS. This article describes the integration of DEFLATE acceleration in z15 into the z/OS software stack in both synchronous and asynchronous mode and presents the resulting performance for selected workloads.