JCL Migration Strategies

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# Example Bash script that converts a simple JCL job to a Linux shell script
#!/bin/bash
 
# Input JCL file
JCL_FILE=$1
 
# Extract job name
JOB_NAME=$(grep -m 1 "^//[A-Z0-9]* JOB" $JCL_FILE | awk '{print $1}' | sed 's/^///g')
 
# Create shell script header
echo "#!/bin/bash" > $JOB_NAME.sh
echo "# Generated from JCL: $JCL_FILE" >> $JOB_NAME.sh
echo "# Migration date: $(date)" >> $JOB_NAME.sh
echo "" >> $JOB_NAME.sh
 
# Extract EXEC statements and convert to commands
grep "^//[A-Z0-9]* EXEC PGM=" $JCL_FILE | while read line; do
  # Get step name and program
  STEP=$(echo $line | awk '{print $1}' | sed 's/^///g')
  PGM=$(echo $line | sed -n 's/.*PGM=\([A-Z0-9]*\).*/\1/p')
  
  echo "# Step: $STEP" >> $JOB_NAME.sh
  echo "echo 'Executing $PGM...'" >> $JOB_NAME.sh
  
  # Based on common program names, generate equivalent commands
  case $PGM in
    IEFBR14)
      echo "# IEFBR14 - No operation" >> $JOB_NAME.sh
      echo ":" >> $JOB_NAME.sh
      ;;
    SORT)
      echo "# SORT operation" >> $JOB_NAME.sh
      echo "sort $INPUT_FILE > $OUTPUT_FILE" >> $JOB_NAME.sh
      ;;
    IDCAMS)
      echo "# IDCAMS equivalent" >> $JOB_NAME.sh
      echo "# Note: Specific IDCAMS commands need manual translation" >> $JOB_NAME.sh
      ;;
    *)
      echo "# Program $PGM needs to be implemented" >> $JOB_NAME.sh
      echo "echo 'Program $PGM not implemented yet'" >> $JOB_NAME.sh
      echo "exit 1" >> $JOB_NAME.sh
      ;;
  esac
  
  echo "" >> $JOB_NAME.sh
done
 
chmod +x $JOB_NAME.sh
echo "Generated $JOB_NAME.sh - review and customize as needed"

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// PARALLEL TESTING APPROACH
 
// ORIGINAL JOB in Legacy Environment
//ORIGJOB  JOB (ACCT),'MONTHLY PROCESS',CLASS=A,MSGCLASS=X
//STEP01   EXEC PGM=BILLING
//INPUT    DD DSN=PROD.CUSTOMER.DATA,DISP=SHR
//OUTPUT   DD DSN=PROD.BILLING.REPORT,DISP=(NEW,CATLG,DELETE),
//            SPACE=(CYL,(10,5),RLSE)
//SYSOUT   DD SYSOUT=*
 
// MIGRATED JOB in Target Environment
# Monthly Billing Job
billing_process:
  schedule: "0 1 1 * *"  # Run at 1:00 AM on the 1st day of each month
  script:
    - name: process_billing
      command: /opt/apps/billing/run_billing.sh
      arguments:
        - --input=/data/customer_data.db
        - --output=/reports/billing_report_$(date +%Y%m).txt
      resources:
        memory: 2G
        cpu: 1.0
 
// COMPARISON VALIDATION
#!/bin/bash
# Script to compare original and migrated job outputs
 
# Copy original job output to comparison directory
scp mainframe:/datasets/PROD.BILLING.REPORT ./original_output.txt
 
# Get migrated job output
cp /reports/billing_report_$(date +%Y%m).txt ./migrated_output.txt
 
# Compare key metrics
echo "Original record count: $(wc -l < original_output.txt)"
echo "Migrated record count: $(wc -l < migrated_output.txt)"
 
# Run detailed comparison
diff original_output.txt migrated_output.txt > diff_results.txt
 
# Check for significant differences
if [ -s diff_results.txt ]; then
  echo "DIFFERENCES FOUND - review diff_results.txt"
  # Send alert for manual review
  mail -s "Billing Job Comparison Differences" team@example.com < diff_results.txt
  exit 1
else
  echo "NO DIFFERENCES - migration validated"
  exit 0
fi

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# JCL Migration Checklist
 
## Pre-Migration Assessment
 
- [ ] Complete inventory of all JCL assets
- [ ] Document job dependencies and scheduling
- [ ] Analyze dataset usage patterns
- [ ] Identify critical path jobs and business cycles
- [ ] Determine migration approach for each workload
- [ ] Create test plan with validation criteria
 
## Migration Execution
 
- [ ] Set up target environment
- [ ] Configure necessary middleware and utilities
- [ ] Migrate reference data and lookup tables
- [ ] Convert JCL by workload group
- [ ] Implement integration points with other systems
- [ ] Develop operational procedures
 
## Testing and Validation
 
- [ ] Execute baseline jobs in source environment
- [ ] Run migrated jobs in target environment
- [ ] Compare outputs and reconcile differences
- [ ] Validate performance characteristics
- [ ] Test exception handling and recovery
- [ ] Perform end-to-end business process validation
 
## Deployment and Transition
 
- [ ] Train operations staff on new environment
- [ ] Conduct user acceptance testing
- [ ] Perform trial cutover and rollback
- [ ] Develop production cutover plan
- [ ] Execute final cutover
- [ ] Monitor initial production runs
 
## Post-Migration
 
- [ ] Monitor system performance
- [ ] Fine-tune operational procedures
- [ ] Document lessons learned
- [ ] Plan for legacy system decommissioning
- [ ] Identify opportunities for further optimization