Enabling job restart functionality

The restart functionality is governed by two environment variables:

ES_JES_RESTART

Setting this variable to Y has the following effects:

ESMAC will display new fields for a job's details on the Output Hold queue, along with a Restart button. The new fields allow you to specify the step and procstep at which the job is to restart.
When the job is run, the lexical files (MFELX*.DAT) associated with the job will no longer be cleaned up when the job is completed; instead, these files will be cleaned up when the job is deleted.

MF_UCC11

Note: This environment variable works independently of the JCL RESTART parameter.

Setting this environment variable to Y or YR enables:

Automatic reset of the GDG bias to the level of the prior run of the job; that is, the restart will automatically pick up the "correct" GDG Bias.
When set to Y, restarting a job with DISP=(NEW,CATLG) datasets will not result in job failure caused by the dataset already being cataloged.
When set to YA, running a job with DISP=(NEW,CATLG) datasets will not result in job failure caused by the dataset already being cataloged.
COND Code Processing and IF/THEN logic that is dependent upon COND codes from prior steps that are skipped by the RESTART will work as expected with no changes to the JCL.

When this environment variable is set to M, when a job is restarted a cataloged dataset is presumed to have an initial disposition of MOD rather than NEW. As a result, any new data is appended to the existing dataset.