Senior Mainframe Developer – COBOL / NaturalOne / ADABAS

We are seeking a skilled Mid-Level to Senior-Level Mainframe Developer to support enhancements to an existing enterprise financial accounting platform running on IBM z/OS.

The developer will be responsible for analyzing, maintaining, and enhancing legacy mainframe applications while implementing new functionality for Composite Reservoir Accounts (CRA).

The project involves developing a pooled-account structure where balances from multiple subsidiary accounts are consolidated into a central reservoir account and distributed based on defined sweep, reverse-sweep, and allocation rules.

The ideal candidate will have strong hands-on experience in Enterprise COBOL, NaturalOne, Natural/ADABAS, JCL, and VSAM, along with experience supporting financial or accounting applications.

Key Responsibilities

• Analyze existing account master, posting, and balance-maintenance programs to identify required application changes.

• Design, develop, and enhance Composite Reservoir Account functionality within existing mainframe applications.

• Implement account opening and closing, participant linkage, sweep and reverse-sweep processing.

• Develop allocation logic, interest apportionment, and closing balance calculations.

• Modify batch COBOL programs and JCL to support nightly and month-end processing.

• Ensure new functionality integrates seamlessly with existing account processing and financial systems.

• Implement audit trails, exception reporting, and reconciliation controls.

• Develop test data, unit testing, regression testing, and parallel-run comparisons.

• Investigate and resolve discrepancies between existing and new processing outputs.

• Analyze legacy code, copybooks, program call chains, and job streams.

• Support implementation, account conversion, and production deployment activities.

• Prepare technical documentation, data-flow diagrams, and operational runbooks.

Required Qualifications

• Strong hands-on experience with Enterprise COBOL development in an IBM z/OS environment.

• Experience working with NaturalOne development environment.

• Good knowledge of Natural programming, including programs, subprograms, maps, and related components.

• Strong experience with Adabas database, including DDMs, descriptors, superdescriptors, and file design.

• Experience with JCL development, debugging, and production batch support.

• Hands-on experience with VSAM file structures and access methods.

• Proficiency in TSO/ISPF, GDGs, JCL procedures, SORT utilities, and batch restart/rerun processing.

• Experience developing or supporting financial and accounting applications.

• Understanding of double-entry accounting, posting processes, balance and accrual maintenance, value dating, reconciliation, and month-end closing.

• Ability to analyze and enhance large-scale legacy applications with limited documentation.

• Strong troubleshooting, analytical, and problem-solving skills.

• Excellent written and verbal communication skills.

Preferred Qualifications

• Experience with cash management, treasury applications, or financial account management systems.

• Knowledge of account pooling, cash concentration, sweep and reverse-sweep processing.

• Experience with interest calculation and intercompany allocation.

• Familiarity with CA-7 scheduling and batch operations.

• Knowledge of REXX, Python, or Java.

• Experience integrating COBOL and Natural applications.

• Familiarity with z/OS Connect, IBM MQ, or REST services.

• Experience with mainframe batch performance tuning and scheduling.

• Ability to work independently and take technical requirements through development, testing, and production implementation.

Technical Environment

Enterprise COBOL | IBM z/OS | NaturalOne | Natural | ADABAS | JCL | VSAM | DB2 | TSO/ISPF | CA-7 | REXX | Endevor | IBM MQ

Additional Requirements

• Ability to work with existing enterprise mainframe applications and follow established change-management processes.

• Experience participating in code reviews, testing, implementation planning, and production support.

• Ability to prepare clear technical documentation and communicate effectively with technical and business stakeholders.