8464axJES3.fm Draft Document for Review February 7, 2020 3:15 pm Processing changes Although no JCL changes are required, a few processing restrictions and limitations are  associated with using the TS3500 tape library in a JES3 environment: GLYPH<SM590000> JES3 spool access facility (SPAF) calls are not used. GLYPH<SM590000> Two calls, one from the prescan phase and the other call from the locate processing  phase, are made to the new DFSMS support module, as shown in Figure C-11 on  page 841. GLYPH<SM590000> The main device scheduler (MDS) processing phases, system select, and system verify  are not made for tape data sets. GLYPH<SM590000> The MDS verify phase is bypassed for TS3500 tape library mounts, and mount processing  is deferred until job execution. Figure C-11 on page 841 shows the JES3 processing phases for CI and MDS. The  processing phases include the support for system-managed direct access storage device  (DASD) data sets. The following important differences exist between TS3500 tape library deferred mounting and  tape mounts for non-library drives: GLYPH<SM590000> Mounts for non-library drives by JES3 are only for the first use of a drive. Mounts for the  same unit are sent by IBM z/OS for the job. All mounts for TS3500 tape library drives are  sent by z/OS. GLYPH<SM590000> If all mounts within a job are deferred because there are no non-library tape mounts, that  job is not included in the setup depth parameter ( SDEPTH ). GLYPH<SM590000> MDS mount messages are suppressed for the TS3500 tape library. 840  IBM TS7700 Release 5.0 Guide