## 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. 

